Speed reducer transmission error testing device and method

The embodiment of the invention discloses a speed reducer transmission error testing method and device. The testing device comprises a base, a test tool, a driving assembly, a detection assembly and a receiving assembly; the test tool is arranged at the output end of a to-be-tested speed reducer; the speed reducer is fixed on the base; the output end of the driving assembly is connected with the input end of the speed reducer, so that the driving assembly is used for driving the input end of the speed reducer to rotate and determining rotation angle information of the input end of the speed reducer; the detection assembly comprises a laser tracker located on one side of the output end of the speed reducer and a target ball arranged on the test tool; the target ball is matched with the laser tracker so as to be used for determining motion trail information of the target ball; and the receiving assembly is used for determining the transmission error of the speed reducer according to the rotation angle informati