Objective To analyze the early predictive value of olfactory function for cognitive decline in older adults with mild cognitive impairment(MCI).Methods From March 2023 to January 2024,convenience sampling was used to select 385 older adults with MCI from two community health service centers in Dongcheng District and Fengtai District of Beijing as participants.Participants were followed up for six months to collect data on general information,olfactory function testing,and cognitive function.According to whether there were changes in clinical cognitive function,older adults were divided into a cognitive function decline group and a cognitive function non-decline group.Binary Logistic regression was used to analyze the independent influencing factors of cognitive decline in older adults with MCI,and the receiver operating characteristic(ROC)curve was used to evaluate the predictive effect of olfactory function on cognitive decline.Results Among 385 older adults with MCI,113(29.4%)experienced cognitive decline.Binary Logistic regression analysis showed that education level,passive cognition activity,social activity,and olfactory dysfunction were independent influencing factors for cognitive decline in older adults with MCI(P<0.05).The area under the ROC curve was 0.819[95%CI(0.773,0.865),P<0.01],with an optimal cutoff value of 9.5 points,a sensitivity of 81.3%and specificity of 31.0%.Conclusions The olfactory function has good predictive value for cognitive decline in older adults with MCI,and can be used for early screening of MCI high-risk individuals with rapid cognitive decline.