In this paper,through the function transformation of four disaster loss indexes about the dead number,the injured number,destroyed buidings and direct economic loss caused by earthquakes,the standards to distinguish these disaster grades by using different loss indexes are unified.The earthquake disaster grades are divided by the grey cluster method,and the different earthquake disaster situations are compared by the sequencing method of the grey associative degree.The disaster grades of 7 important earthquakes in Chinese mainland from 1966 to 1983 and 17 earthquakes in Chinese mainland in 1995 are divided and their disaster conditions are compared by using the methods.The results show that the methods basically can evaluate quantitatively and accurately the seismic damage situation.