Abstract: Objective: To investigate the current status and influencing factors of medical service utilization among older adults in integrated care institutions, aiming to provide an empirical basis for optimizing the allocation of medical resources and enhancing health management for older adults. Methods: A cross-sectional survey was conducted from October to December 2024, employing stratified sampling to recruit 395 elderly residents from 10 integrated care institutions in the cities of Nanning, Guilin, and Yulin. The random forest model was used to rank the importance of influencing factors, combined with LASSO regression for variable selection. Significant variables were subsequently incorporated into a multivariate logistic regression model for analysis. Results: The utilization rates for outpatient and inpatient services were 42.5% and 32.4%, respectively. Multivariate analysis revealed that health checkups (OR=2.107, P=0.007) and pain (OR=2.447, P=0.000) were significant promoting factors for outpatient service utilization, whereas a travel time to the hospital of ＜10 minutes (OR=1.988, P=0.026) significantly increased outpatient utilization. A history of falls (OR=2.822, P=0.000) was a strong influencing factor for inpatient service utilization, while female gender (OR=0.480, P=0.006) was associated with a lower probability for inpatient service utilization. In terms of outpatient service utilization, common family diseases and genetic diseases ranked high in the random forest model, while for inpatient service utilization, a history of falls and education level ranked prominently in the model. Conclusion: Medical service utilization among older adults in integrated care institutions in Guangxi is jointly influenced by health needs, service accessibility, health beliefs, and sociodemographic characteristics. To enhance the efficiency and equity of service utilization, it is recommended to strengthen health management, optimize service layout, implement health education, and focus on vulnerable groups.