The invention relates to a high-speed train gear box running-in test platform, in particular, a wheel-set axle clamping support device of a high-speed train gear box running-in test bench. The wheel-set axle clamping support device is mainly composed of a double-bearing elastic sleeve clamping main axle assembling body (1), a double-bearing single-bearing seat upper and lower body (2), a bearing seat height-increasing and broadening supporting seat (3) and a flange type conical hole coupling (4); and a double-bearing elastic sleeve clamping main axle (8) is a five-section stepped shaft and includes a flange type coupling connection shaft (15), a round nut connecting shaft (16), a bearing installation shaft (17), an axle radial clamp elastic sleeve mounting shaft (18) and a clamping main axle elastic sleeve locking nut connecting shaft (19). With the wheel-set axle clamping support device of the invention adopted, the problems of complicated disassembly and installation, damage to the journal of a wheel-set axle and incapability of adapting to high test speed of an existing wheel-set axle clamping support device of the high-speed train gear box running-in test bench can be solved, and requirements for reliable proceeding of a high-speed train gear box running-in test can be satisfied.