In studying the contents of Hoek-Brown strength criterion

it is easy to discover that the complicated failure of engineering rock under loads is generalized to tensile and shear failures

and that factors affecting the rock strength are interpreted with two empirical parameters in the criterion

m ( the degree of stiffness of rock) and s ( the degree of failure of rock). So there is much practical value in engineering to study the two parameters m and s that influence the strength of rock. To satisfy the digital accuracy of engineering

the article mainly describes the regulation of the parameters

influencing the accuracy of strength value of rock masses; meanwhile it points out that there is important meaning and value to raise the accuracy of the two empirical parameters. Also this paper is beneficial to applying the standard to engineerings.