The deep rock engineering is characterized with high ground stresses

high earth temperatures and high pore pressures so that the traditional RMR method has many limitations in the evaluation of the quality of surrounding rock masses.The marking standards of 3 indexes including uniaxial compressive strength of rock

rock quality designation and joint space in the traditional RMR method are revised by combining the groundwater and ground temperature weakening factors defined considering the effect of the underwater of high pressure and high earth temperature on the mechanical characteristics of rock mass and a nonlinear continuous regressive function relating the values of 3 indexes to their marking values is gained.Then

the risk degree factor of rock mass damage is also defined on the basis of the value of the ground stress

rock strength and the corresponding relationship between their values

and the revised marking values of rock mass quality is built.Finally

an improved comprehensive RMR method is gained

which is appropriate for the evaluation of the surrounding rock quality in deep rock engineering.A case study shows that the revision method is reasonable and efficient.