Artificial shale sample preparation method in shale stability index(SSI) evaluation test was improved.With shale powder in B28 well,the optimum preparation condition of shale sample in SSI test was obtained.The slug was suppressed under 10.5 MPa to get shale sample with 14.03% water content which simulated the formation of high water content,and dry shale powder was suppressed under 10.5 MPa to get shale sample with 1.91% water content which simulated rock samples with low moisture content of deep formation.The optimum experiment conditions of SSI test was established: immersing in test solution at 65 ℃ for 8 h and then measuring SSI value of the shale sample.The results of scanning electron microscopy(SEM) micro-structural analysis showed that the micro-pore scales of shale samples in the two preparation method were similar to that of actual rock shale.Water content of high water content shale sample was similar to that of actual shallow shale formations which was of 12%—14%.Water content of low water content shale sample was similar to that of actual deep shale formations which was of 2%—3%.Relative error of the improved SSI evaluation method was of 2.91% which showed good parallel of the method.The improved method could effectively evaluate anti-collapse effects of anti-sloughing agents and anti-collapse systems and help understand mechanisms.