Churning power losses account for a larger proportion of power consumption in diplubricated transmission gears,which is one of the main factors leading to lubrication failure.In order to forecast churning power losses for the gears immersed in lubricating oil in variety of work situations,a new multifunction gear box churning torque loss tester was designed,and the experimental methods for different churning power loss experiments were introduced,including churning power loss experiment of different tooth profile gears,churning power loss experiment of gears and discs,churning power loss experiment of nonstandard spur gears.The tester could be used to study the influence to churning power losses by changing the gear size change or other factors by the churning power loss experiment of different tooth profile gears and nonstandard spur gears,to investigate the churning power losses in the meshing zone by the churning power loss experiment of gears and discs.