Abstract: When the mine has no rock mass exploitation project, the rock mass stability index cannot be determined because of the pertinent parameters of the rock mass basic quality cannot be directly measured.In this paper, the drilling cores are taken as the research object.The point load strength index and the rock quality designation RQD are calculated for each drilling cores.And the continuously distributed index of rock mass basic quality is obtained in each borehole, based on the relationship between rock point load strength and uniaxial compressive strength, and the relationship between rock quality designation RQD and intactness index of rock mass.Taking the rock mass basic quality of each borehole as the data source, the rock mass basic quality of the whole orebody is estimated by means of SURPAC block model and inverse distance weight method.And the spatial distribution of rock mass basic quality of orebody is constructed.The research results provide a method for determining the rock mass basic quality index and rock mass stability, and provide a basis for selection of mining methods, development work and mining preparation.