The invention discloses a precision speed reducer accuracy and performance comprehensive test bed. A driving motor 1, a first coupler 2, an input end torque sensor 3, a second coupler 4, an input endangle measuring module 21, a tested speed reducer 5, an output end angle measuring module 22, a third coupler 6, an output end torque sensor 7, a speed increasing machine 8 and a loading motor 9 are sequentially connected on a bed base 19 along the same axis, the driving unit is fixedly connected on an X-axis driving and supporting platform 18, the input end angle measuring module, the output endangle measuring module and the tested speed reducer 5 are connected on a mounting and clamping support 15, and a loading unit is fixedly arranged on a loading and supporting platform 14. The test bedmeets the testing requirements of transmission performances such as precision speed reducer angle transmission errors, torsion rigidity, back clearances, return differences, retrace errors, no-load starting torques, no-load friction torques, reverse starting torques, mechanical efficiency, temperature rising and no-load running-in, on-load tests and overload tests, and the test bed is high in testing function comprehensiveness and high in testing efficiency and testing accuracy.