OBJECTIVE To evaluate the efficacy and safety of four cyclin-dependent kinase 4/6 （CDK4/6） inhibitors （dalpicilib， abemacilib， ribocilib， palbocilib） combined with endocrine drugs in the treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative （HR+/HER2－） breast cancer. METHODS Computer searches were conducted on PubMed， the Cochrane Library， Web of Science， Embase， CNKI， Wanfang data and VIP to collect randomized controlled trials （RCTs） about CDK4/6 inhibitors combined with endocrine drugs （trial group） versus endocrine drugs alone or combined with placebo （control group）. The search period was from the establishment of the database to April 2023. After literature screening， data extraction and quality evaluation， a meta-analysis was conducted by using RevMan 5.4.1 software. RESULTS A total of 22 articles were included， involving 15 RCTs with a total of 18 574 patients. The meta-analysis results showed that the progression free survival [HR＝0.77， 95%CI （0.74， 0.79）， P＜0.000 1]， overall survival [HR＝0.91， 95%CI （0.87， 0.94）， P＜0.000 01]， objective response rate [OR＝1.71， 95%CI （1.51， 1.93）， P＜0.000 01] and clinical benefit rate [OR＝1.73， 95%CI （1.52， 1.95）， P＜0.000 01] of the trial group were significantly better than control group. The incidence of adverse drug reactions≥3 levels [OR＝10.28，95%CI （6.97，15.17），P＜0.000 01]， neutropenia [OR＝65.09， 95%CI （36.43， 116.31）， P＜0.000 01]， leukopenia [OR＝22.90， 95%CI （15.40， 34.04）， P＜0.000 01]， anemia [OR＝5.71， 95%CI （4.51， 7.22）， P＜0.000 01]， diarrhea [OR＝ 3.00， 95%CI （1.19， 7.51）， P＜0.05] and nausea [OR＝1.99， 95%CI （1.52， 2.60）， P＜0.000 01] in the trial group was significantly higher than control group. CONCLUSIONS The combination of CDK4/6 inhibitors and endocrine drugs has a significant effect on HR+/HER2－ breast cancer， with a high incidence of adverse reactions， especially hematotoxicity.