Based on a lot of testing data from Xiluodu Hydropower power station and ertan hydropower staton,the parameters such as m and s of the Hoek Brown strength criterion are analyzed in this paper.It is found that m and s are a couple of variables with great corelativity.While the strength of rockbody is a constant,there is negative correlativity between m and s determined by the property and location of rockbody,it is suggested in the paper that the corelativity between m and s is very important parameter which can not be neglected.