Based on aggregated data on cross-regional medical treatment under Anhui Province’s medical insurance scheme for 2021–2024, this study uses descriptive statistics, comprehensive incremental factor analysis, service-type growth contribution analysis, and structural change analysis to examine the sources of expenditure growth and changes in service structure. Total expenditure rose from 32.322 billion yuan to 48.218 billion yuan, the number of visits increased by 365.58%, and the cost per visit decreased by 67.96%. The volume effect was 20.092 billion yuan, and the per-visit cost effect was ?4.195 billion yuan. Inpatient care contributed 76.57% of the expenditure increase, while general outpatient and emergency care accounted for 83.73% of the increase in visits. Changes in the distribution of visits across service types were greater than changes in the expenditure distribution. Expenditure growth was mainly driven by increased service utilisation, while the decline in overall cost per visit was associated with the shift towards general outpatient and emergency care. The findings suggest classifying cross-regional medical needs by disease characteristics, strengthening the management of continuous cross-regional outpatient service utilisation, analysing inpatient flows and local service gaps by DRG/DIP groups, and improving classified evaluation and its feedback mechanisms for regional medical insurance policy adjustment.