Objective To compare the effect of unrestrictive visiting policy(UVP) and restrictive visiting policy(RVP) on delirium, length of hospital stay, acquired infection, as well as anxiety and depression of patients in intensive care unit (ICU), explore the optimal visiting mode. Methods Relevant researches were retrieved from Cochrane Library, PubMed, Embase, Web of Science,Chinese Biomedical Literature Database, Wanfang Database, China National Knowledge Infrastructure(CNKI) and VIP Database,the deadline was March 31, 2019. Quality of literatures was strictly evaluated and data were extracted by two researchers, literatures which conformed to the inclusion criteria were performed Meta-analysis. Results A total of 18 literatures (13 Chinese and 5 English) were included in this study, 8 were randomized controlled trial (RCT) studies and 10 were quasi-experimental studies, 4 728 patients were included. The included studies were divided into subgroups according to study design and length of visiting, forest plot result showed that compared with RVP, UVP could effectively reduce the incidence of delirium in ICU patients (OR=0.19, 95% CI[0.15, 0.24], P<0.001), reduce ICU patients' anxiety (MD=-1.60, 95% CI[-1.67, -1.54], P<0.001) and depression (MD=-1.63, 95% CI[-2.76, -0.49], P=0.003), as well as effectively improve patients' relatives' satisfaction to health care workers in ICU (OR=3.56, 95% CI[2.32, 5.48], P<0.1); meanwhile, UVP didn't increase the incidence of ICU-acquired infection (OR=0.82, 95% CI[0.55, 1.21], P=0.31), ICU mortality (OR=0.61, 95% CI[0.21, 1.79], P=0.37), and length of hospital stay(MD=-0.40, 95% CI[-1.29, 0.50], P=0.39). In addition, without considering the study design, UVP could reduce the incidence of ICU-acquired infection (OR=0.65, 95% CI[0.51, 0.82], P=0.004), the longer the visiting duration, the lower the incidence of ICU-acquired infection (OR=0.75, 95% CI[0.61, 0.91], P=0.004). Conclusion UVP does not increase the incidence of ICU-acquired infection, length of hospital stay and mortality, but can effectively decrease the incidence of ICU patients' delirium, reduce critically ill patients' anxiety and depression, and improve ICU patients' relatives' satisfaction.