Objective:To explore the impact of multimorbidity on disability in older adults, providing a reference for formulating strategies for the management and nursing of multimorbidity and disability in older adults.Methods:Adopting the method of cross-sectional survey research, the data of 6 469 older adults (≥60 years old) were collected from the 2018 Chinese Longitudinal Healthy Longevity Survey database in July 2023, including basic information, chronic disease prevalence, and disability measured by basic activities of daily living (BADL), and instrumental activities of daily living (IADL). They were divided into multimorbidity and non-multimorbidity groups based on whether they had two or more chronic diseases. The propensity score matching (PSM) method was used to match the basic conditions of the two groups of older adults with the proportion of 1∶1. Binary logistic regression was applied to analyze the effects of multimorbidity on BADL disability and IADL disability.Results:Among 6 469 older adults, there were 2 882 males and 3 582 females, with 3 158 aged 60-84 years old and 3 311 aged over 84 years old. BADL disability accounted for 26.5% (1 712/6 469), while IADL disability accounted for 66.8% (4 324/6 469). There were 2 335 patients in the multimorbidity group and 4 134 patients in the non-multimorbidity group. Binary Logistic regression analysis showed that the risk of BADL disability in older adults in multimorbidity group was 1.511 times higher than that in the non-multimorbidity group (95% CI 1.317-1.734, P<0.01); the risk of IADL disability in older adults in the multimorbidity group was 1.618 times higher than that in the non-multimorbidity group (95% CI 1.426-1.835, P<0.01). Conclusions:Multimorbidity would increase the risk of disability in older adults. Relevant authorities should develop relevant interventions and nursing responses to enhance the prevention and management of multimorbidity and disability in older adults.