［Objective］Compared to metro, city rapid transit lines are characterized by longer routes and greater passenger travel distances. Operating express/local trains can increase travel speed and improve travel efficiency for passengers. Therefore, it is necessary to study the passenger flow impact of such express/local train operation plans and analyze the travel characteristics of passengers on these lines.［Method］Guangzhou Metro Line 21 (identified as a city rapid rail transit line) is selected as the research object to analyze the passenger flow adaptability of this line operation plan and describe its current operating conditions. Based on the line′s entry/exit smart card data, the temporal distribution characteristics of passenger trips under the current express/local train operation plan are analyzed. A 3-minute interval passenger flow matrix is extracted as the input for modeling. Using VISUM software, a timetable-based passenger flow assignment model is established to output passenger flow indicators for the express/local train operation plan. Problems of the current plan are analyzed and directions for optimization are identified.［Result & Conclusion］The current express/local train operation plan on this line demonstrates significant time-saving effects. The express train has a strong appeal to peripheral passenger flow, with a clear boarding peak appearing at peripheral stations before the express train departure. To further optimize the operation plan, issues such as long intervals between express trains and inconvenient interchanges between express and local services should be addressed.