Abstract: Objective: Many tram lines in the southwest region of China have longlarge downhill ramps. To ensure the safe operation of trams on longlarge downhill ramp, speed limits need to be imposed, which in turn affect the travel time. Therefore, it is necessary to study the impact of longlarge downhill ramp segment speed limit on tram travel time. Method: Based on tram traction calculation and interval travel time calculation, a simulation model for interval operation is constructed using Opentrack software. Taking the example of Lijiang Tram Line 1, the minimum tram travel time in different schemes of longlarge downhill ramp segment speed limit is calculated using an optimization solver. Based on the interval operation simulation model, a route simulation test is conducted to evaluate the segment passing capacity and further quantitatively analyze the impact of different speed limits on train travel time. Result & Conclusion: Based on the simulation test results, if the longlarge downhill ramp speed limit is reduced by 50%, the line passing capacity decreases by approximately 17%. The smaller the speed limit, the longer the train travel time and the lower the capacity of segment passing.