The invention relates to a testing device for material wear of cycloidal gear and needle bearing of RV reducer, comprising: an upper cover (1), a lower cover (2), two sliding shafts (3 and 3′), two connecting shafts (4 and 4′), a driven shaft component (5), two copper sleeves (6 and 6′), two nuts (7 and 7′), two disc springs (8 and 8′), an eccentric shaft component (9), a needle bearing (10), two planetary gears (11 and 11′), two cycloidal gears (12 and 12′), and a motor assembly (13). The device can be installed on various industrial platforms. The motor drives the planetary gear to rotate, and then drives the eccentric shaft to rotate. The first bearing hole of the cycloidal gear fits with the needle bearing and forms a revolute pair with the eccentric shaft. Owning to the eccentric shaft, the cycloidal gears (12 and 12′) are driven to swing. The other bearing hole fits with the sliding shaft (3 and 3′) and the connecting shaft (4 and 4′) to form a loaded rolling friction pair. Then the cycloidal gear drives the sliding shaft to perform reciprocating movement along the track of cavity. The connecting shaft (4 and 4′) and the sliding shaft (3 and 3′) exert the load on the cycloidal gear (12 and 12′) and needle bearing (10) by compressing the disc springs via the nuts. After a specified time of operation, measure the diameter of bearing holes of cycloidal gear and the outer diameter of needle bearing, then evaluate the material wear of the two components. It provides reliable testing data for the selection of material and the determination of heat treatment process of the cycloidal gear and needle bearing. The invention solves the difficult problem for measuring the material wear of cycloidal gear and needle bearing, which are the key components of RV reducer.