The invention provides a 
strain gauge pasting device and method for 
harmonic reducer fault diagnosis. The 
strain gauge pasting device comprises a base 
flange assembly, a force control 
assembly, a telescopic rod with a seat 
cushion and a 
compression screw. The base 
flange assembly comprises a mounting 
flange cover, a boss with a threaded hole and a supporting seat with a hole, the boss with the threaded hole and the supporting seat with the hole are mounted on the flange cover through screws, and the mounting flange cover is buckled on a 
harmonic speed 
reducer in a matched mode through an inner hole; the force control assembly comprises a pressing cover, a pressure-bearing seat and a spring assembly, and the distance between the pressing cover and the pressure-bearing seat can be controlled through a telescopic spring; the telescopic rod with the seat 
cushion penetrates through the pressure-bearing seat and the pressing cover and is embedded into the mounting flange cover, and the bottom of the telescopic rod with the seat 
cushion is used for fixing the resistance 
strain gauge; and the 
compression screw penetrates through the pressing cover and is fixed to the boss with the threaded hole. When the strain gauge pasting device is used, the strain gauge is fixed to the seat cushion at the bottom of the telescopic rod, after glue is dripped, the elastic force of the spring is adjusted by the 
compression screw, so that the telescopic rod is controlled to move, and the compression and pasting of the strain gauge are completed.