Abstract: The difference between the samples affects the discreteness of the direct shear test results and more importantly the rationality of the analysis results of the shear strength parameters of the multiple test sample method of jointed rock mass. For this reason, the single-joint sandstone samples are prepared by using the splitting method, and the joint surface morphology scanning analysis and direct shear tests are carried out. The results indicate that: (1) Due to the limitation of the sample preparation conditions, the difference between the samples is unavoidable. The non-uniformity of the samples leads to the discreteness of the test results, so that the order of use of the samples directly affects the distribution of the test results. (2) Based on the empirical formula for the shear strength of joint surfaces established by Barton, a single test sample method is proposed to determine the JRC and shear strength parameters of the joint surface of the samples through the scanning analysis of topography of single sample joint surface or single direct shear test, so as to provide a better idea for quantitative analysis of the difference in shear strength parameters between the same sample. (3) A comprehensive analysis method for the shear strength of jointed rock mass based on the single sample method is proposed. The shear strength test values and calculated values of the same set of samples under different normal stresses are fitted together, so that the shear mechanical properties of the samples under different normal stresses are reflected. It can more accurately reflect the distribution of shear mechanical properties of the joint surface of the samples, and can eliminate the influences of the order of use of the samples on the test results.