The strength reduction method based on the generalized Hoek-Brown failure criterion is studied. Two basic standards judging the rationality of the strength reduction method are proposed as follows: it coincides with strength reduction method based on the Mohr-Coulomb criterion and represents the real failure characteristics of jointed rock. Based on the two standards

three kinds of strength reduction methods are contrasted by reducing σci and mi

σci and GSI

and mi and GSI with the same factor. Analysis results indicate that the method of reducing mi and GSI with the same factor is more reasonable. Through comparative study of one engineering case

the method of reducing mi and GSI with the same factor can represent real failure characteristic of fractured rock is proved; and then more reliable safety factor during the stability analysis of rock slope is obtained.