In order to investigate the failure causes of spherical roller bearings of a generating set,the new grease,used grease and the damaged bearings were tested and analyzed by means of emission spectroscopy,ferrography,SEM energy spectrum and simulation test.It is found that the reasons for the failure of spherical roller bearings are that the antiwear properties of new grease is decreased during storage,and the grease is damaged by water pollution and can not be added regularly during the bearing running process.These reasons causes the high temperature oxidation of the surface of friction pairs and the damage of bearings.The improvement measures were put forward,such as choosing the grease that meets the requirements and adopting a method of regular adding grease.The spherical roller bearings operate normally after improvement.