The invention provides a detection line for railway vehicle speed-reducing equipment. The detection line consists of a windlass, a traction buffer, a testing vehicle, a wheel sensor, a speed sensor, a pressure sensor, a displacement sensor, a detected equipment assembly clamp, an industrial control computer and a rail with an accelerating slope, a flat slope and a speed-reducing slope. The testing vehicle is rolled by using rail height difference, the position of the wheel sensor is changed, and the power supply of the windlass is cut off in time, so that different rolling speeds of the testing vehicle can be obtained. Technical data of the tested equipment can be acquired by various sensors, and a detection result is output through computer operation by utilizing special software. The detection line can detect and record the comprehensive performance of various types of railway vehicle speed-reducing equipment, and can replace the traditional detecting method of pushing trucks by virtue of the railway vehicle or locomotive.