Objective:To systematically evaluate the safety and effectiveness of sequential humidified high flow nasal cannula (HFNC) therapy in ICU patients after mechanical ventilation withdrawal.Methods:Cochrane Library, PubMed, Medline, Embase, Web of Science, Scopus, ProQuest, SinoMed, Chinese National Knowledge Infrastructure (CNKI) , Wanfang Data and VIP were searched by computer for randomized controlled trials (RCTs) or clinical controlled trials of HFNC in ICU patients after mechanical ventilation withdrawal. The retrieval time was from the establishment of the database to November 1, 2020, and the included references were tracked. Two researchers strictly evaluated the quality of literature and extracted data. RevMan 5.3 software and Stata 14.0 software were used for Meta-analysis.Results:A total of 14 articles were included. Meta-analysis showed that, compared with conventional oxygen therapy and noninvasive positive pressure ventilation, HFNC could reduce the partial pressure of carbon dioxide (PaCO 2) [combined SMD=-0.21, 95% CI (-0.32- -0.10) , P=0.000 3], reduce the incidence of respiratory failure [combined RR=0.72, 95% CI (0.61-0.85) , P=0.000 1], reduce the respiratory rate of patients while removing the source of heterogeneity [ SMD=-0.44, 95% CI (-0.86- -0.03) , P<0.05]and improve the oxygenation index of patients while removing the source of heterogeneity [ SMD=-0.34, 95% CI (-0.56- -0.12) , P<0.05]. Conclusions:HFNC can support the oxygenation demand of ICU patients after mechanical ventilation weaning, but it still needs higher treatment and nursing standards to promote its clinical application.