Abstract:Objective To systematically review the relationship between olfactory dysfunction (OD) and cognitive function in Parkinson's disease (PD). Methods Databases including CNKI, Wanfang Data, SinoMed, PubMed, Embase, Cochrane Library and Web of Science were electronically searched from inception to November 2021 to collect case-controlled trials (CCTs) on the relationship between olfactory function and cognitive function in the patients with PD. After the CCTs were screened and assessed based on inclusion and exclusion criteria, Meta-analysis was performed by using Revman 5.4 and Stata 14 software. Results Finally, 1 568 patients were involved in 10 CCTs, including 884 cases in PD-OD group and 684 cases in PD-NOD group. Meta-analysis showed that compared with PD-NOD group, the cognitive score ［SMD=-0.45，95%CI （-0.62，-0.28），P<0.01］ and the scores in memory ［SMD=-0.71，95%CI（-0.90，-0.51），P<0.01］, execution ［SMD=-0.46，95%CI（-0.80，-0.12），P<0.01］, language ［SMD=-0.41，95%CI（-0.71，-0.11），P<0.01］,attention and working memory ［SMD=-0.27，95%CI（-0.48，-0.06），P<0.01］and visual-spatial function ［SMD=-0.45，95%CI（-0.78，-0.11），P<0.01］significantly decreased in PD-OD group. Conclusions Olfactory dysfunction is associated with cognitive impairment in PD patients. The interventions to promote cognitive function in PD patients should focus on individuals who have developed olfactory dysfunction.