To establish early warning indicators for Chinese nurses to recognize in-hospital cardiac arrest (IHCA) of adult inpatients. Computer retrieval of Chinese and English databases such as CNKI, Wanfang Database, VIP, National Medical Library of the United States PubMed Database, Web of Science, Embase Database of the Netherlands Medical Abstracts, Cochrane Library Database and other international guidelines collaboration network (GIN), National Institute for Health and Clinical Optimization (NICE), Scottish Intercollegiate Guidelines Network (SIGN), BMJ best clinical practice and other guidelines was performed. The retrieval time limit for respiratory and cardiac arrest early warning indicators or risk identification related content of the adult inpatient in the professional website was until June 30, 2020. After literature research and expert group analysis, the research group drew up an expert correspondence questionnaire, and selected 32 medical and nursing experts from Beijing, Tianjin, Jilin, Shandong, Shaanxi, Sichuan, Zhejiang and other grade three first-class general hospitals from July to September 2022. The Delphi method was used to conduct two rounds of expert correspondence, forming the final version of the early warning index of cardiac arrest in adult inpatients. Five first-level indicators, 23 second-level indicators and 41 third-level indicators including vital signs, consciousness and pupils, postoperative blood drainage volume, lab results and other five aspects were initially formed. The effective response rates of the two rounds of expert correspondence were 100% (32/32) and 93.75% (30/32), respectively, the Kendall coordination coefficients W of the first round and the second round were 0.340 and 0.462, respectively, the expert authority coefficients Cr were 0.88 and 0.89, respectively, the mean value of importance assignment was 3.94-5.00, 4.07-5.00, and the coefficient of variation was 0-0.16, 0-0.14, with statistically significant differences (all P < 0.05). Finally, 5 primary indicators, 23 secondary indicators and 43 tertiary indicators were formed, including five aspects of vital signs, consciousness and pupils, postoperative blood drainage, lab results, symptoms and chief complaints. The expert consultation on the early warning indicators of IHCA for adult patients tends to be consistent and scientific, which is applicable to help nurses detect the changes of patients' condition as early as possible.