Objective: To retrieve, evaluate and summarize the best evidence of warning indicators of in-hospital cardiopulmonary arrest among adults, and to provide evidence-based basis for early intervention on in-hospital cardiopulmonary arrest. Methods: Guidelines websites and databases including the BMJ best practice, UK National Institute for Health and Clinical Excellence, International Guidelines Collaboration Network, Scottish Interscholastic Guidelines Network, China Clinical Guideline Library, CNKI, Wanfang, VIP, Cochrane Library, PubMed, Web of Science, Embase etc. were retrieved. Literatures including guidelines, expert consensus, systematic reviews with regard to in-hospital cardiopulmonary arrest among adults were included. The corresponding quality evaluation tools were used to evaluate the quality of included literatures. The retrieval time limit was from the inception of databases to June 30, 2022. Results: Five guidelines, one expert consensus, and 12 systematic reviews were included. A total of 27 pieces of the best evidence were extracted, covering 5 aspects including main vital signs, electrocardiographic, test indicators, symptoms and chief complaints，and medical history.Conclusion: This study summarized the best evidence of warning indicators of in-hospital cardiopulmonary arrest among adults. Further translation and application of these evidence based on the current situation of domestic clinical practice is needed and the suitability needs further evaluation.