The invention relates to a rail vehicle transmission parameter detection test device, and specifically relates to a reliability test bench of a high speed train transmission gear box. The test bench is composed of a non-vibration shaft assembly assembling body (1), a No.1 gear box fixing frame assembling body (2), a vibration shaft assembly assembling body (3), a No.2 gear box fixing frame assembling body (4), an installation platform assembling body (5) and a transmission shaft assembly assembling body (6). The non-vibration shaft assembly assembling body (1) and the vibration shaft assembly assembling body (3) are identical in structure, and the No.1 gear box fixing frame assembling body (2) and the No.2 gear box fixing frame assembling body (4) are identical in structure. On the premise that data required by the test is precisely measured, a vibration shaft is divided into three segments, and on the premise that other shaft segments are not damaged, only the damaged shaft segments are changed, so that the time is saved and the efficiency is improved in a changing or maintenance process. The test bench is reasonable in structure, and the test efficiency is substantially improved.