Objective To explore the early clinical characteristics and influencing factors in children with autism spectrum disorders(ASD). Methods From January 2005 to December 2014, 193 children with ASD were collec-ted by continuous grouping method from Children′s Rehabilitation Training Center in Xi′an.According to the 11 matched case-control study requirements, and the other 193 children from kindergartens and primary schools in the urban areas of Xi′an were collected as healthy control group from March 1 to July 1, 2016.The age of children in the case group was (40.78±14.86)months and the age of the healthy control group was (40.61±14.40) months.There were 167 boys and 26 girls in 2 groups and the ratio of boys to girls was 6.421.00.The general status questionnaires, medical history questionnaire, diagnostic chart, Autism Behavior Checklist(ABC) and Family Environment Scale of Chinese version(FES-CV) were completed by parents between 2 groups.Childhood Autism Rating Scale(CARS) was completed by doctors in the case group.By using Excel software, the original questionnaires were completed in 2 entries by 2 persons to set up the database.All data were analyzed by SPSS 17.0 statistical software and conditional Logistic regression was used for multivariate analysis. Results Seventy point eight percent(137/193 cases)of children with ASD had been found abnormal under 2 years old or at 2 years old, and 54.9%(106/193 cases)had been diagnosed under 3 years old or at 3 years old.The average delay from the discovery to the diagnosis was 17 months.The initial abnormalities appea-rances were mainly manifested as no response to calling in 153 cases(79.3%), very little active contact with others in 141 cases(73.1%), silent or less use of oral language in 137 cases(71%), avoiding contact with the eyes of others or lack of facial expressions in 121 cases(62.7%). Their signs were easy to be misdiagnosed as mental retardation and language retardation.Children in the case group began to walk alone at the age of 8 months to 3 years old, and only 62.2%(120/193 cases) of them could walk alone at the age of 18 months or before.The age of conscious speech was at 8 months to 4 years and 4 months, and only 39.4%(76/193 cases) of the ASD children could speak at the age of 18 months or before.The total scores of the ABC scale of the case group were (56.520±22.140) scores and the sub-scales and total scores were significantly higher than those of the healthy control group, and the difference was statistically significant(t=16.845, 27.390, 16.527, 26.320, 23.371, 32.206, all P<0.001). The positive consistent rate of ABC and clinical diagnosis was 56.5%.The total scores of CARS in the case group was(36.4±8.6) scores, and the positive consistent rate of CARS and clinical diagnosis was 78.8%.There was a statistical significance between the 2 groups in parental education, mother′s occupation, family history(χ2=29.670, 44.593, 15.439, 6.095, all P<0.05), and there were statistical significance in the main caregivers, family harmony and family income(χ2=19.006, 7.129, 109.027, all P<0.05). There was no statistical significance between the 2 dimensions of independence and achievement orientation between the 2 groups(t=-1.559, -0.139, P=0.120, 0.890). The case group in the family cohesion, expressiveness, intellectual-cultural orientation, active-recreational orientation, moral-religious emphasis, organization and control of the 7 dimension scores were significantly lower than those in the healthy control group, and the differences were statistically significant(t=-7.683, -5.734, -8.762, -14.109, -2.026, -4.530, -2.464, all P<0.05). In the case group, the scores of the conflict dimension were higher than those of the healthy control group, and the difference was statistically significant(t=4.925, P<0.001). There was a statistical significance between the 2 groups in gestational age and birth hypoxia(χ2=6.898, 27.180, all P<0.05). According to multivariate analysis of Logistic regression, people other than parents serving as the primary support, anoxia of newborn, mother of non professional and technical personnel and lower scores of family active-recreational orientation might be the risk factors of ASD, family per capita income of 3 000 Yuan RMB or more monthly, mother education level of high school and above, and lower scores of family conflict might be the protective factors for ASD. Conclusions Clinical features of most ASD children can be easily identified under 2 years old, but if the diagnosis is delayed, the related intervention is late, so importance should be attached to early diagnosis.Mother′s occupation and education level, family economic status, family environment, their supervisors, and anoxia of newborn may be the effective entry points in the prevention and treatment of ASD. Key words: Autism spectrum disorders; Clinical features; Risk factors