Abstract: Rockmass strength parameters depend to some extent on stress values acted on the rockmass. Strength parameters of rockmass, which have the same rock properties and structure, are different because of different stress values acted on the rockmass in the space distribution. Based on the slope deformation process analysis, slope stress spatial distribution is evaluated and influence of rockmass strength parameters is revealed in the process of slope deformation evolvement. The study plays an significant role in stability evaluation and engineering optimization design. Taking the rockmass in upper dam site of Shannipo hydropower station as an example, based on partition of engineering geology petrofabric, primary shear strength parameters of rockmass are estimated by Hoek-Brown criteria. Geological mechanical model, for which original topographty is renewed, is established. According to slope deformation process, spatial distribution properties of stress values are discussed by FLAC3D software. A subdivided engineering geological petrofabric, from which slope stress properties are considered, is determined and strength parameters, which made the result more reasonable, are estimated.