Investigate the relationship between anxiety, depression and social support of caregivers of mentally retarded children, and provide further reference for their positive development. <i>The Social Support Rating Scale</i> and <i>General Hospital Anxiety and Depression Scale</i> were conducted among 111 caregivers of mentally retarded children in three special education institutions in a district of Chongqing by cluster sampling. SPSS22.0. was used to statistical analysis. The incidences of anxiety and depression in caregivers of mentally retarded children were 52.3% and 53.2% respectively. Caregivers of mentally retarded children in non-anxiety group and non-depression group scored significantly higher in subjective support, objective support, and total social support than those in obvious anxiety group and obvious depression group. Social support (γ=-0.392, γ=-0.390) and subjective support (γ=-0.335, γ=-0.325), objective support (γ=-0.306, γ=-0.321) and support utilization (γ=-0.235, γ=-0.224) for caregivers of mentally retarded children were negatively correlated with anxiety and depression. Multiple linear regression analysis showed that subjective support and objective support had negative effects on anxiety and depression. The anxiety, depression and social support of parents of mentally retarded children will interact each other. And providing diversified and service-oriented social support is conducive to alleviate their anxiety and depression, then promote their positive development.