Abstract: In view of the frequent occurrence of core disking in borehole under high in-situ stress in deep rock engineering, which leads to the difficulty of intact core sampling on site, the rock and ore fragments after stope blasting are selected for point load test. Two correction coefficients of exponential type and linear type (and) are used to modify the point load strength index, and the modified point load strength index is and . Then the distribution characteristics and laws of the point load strength index before and after modification are obtained: The distribution frequency of point load strength index before and after modification basically meets normal distribution, the point load strength index before modification basically presents skewness distribution, and the point load strength index after modification basically presents standard normal distribution. With 95% confidence, the results obtained by linear correction coefficient are more accurate. The confidence interval of point load strength index at standard point of rock sample is 1.09~1.57MPa, and the mean value is 1.33MPa. The confidence interval of the ore sample is 0.37~0.45MPa, and the mean value is 0.39MPa. Because the samples are affected by blasting disturbance with some internal damage degree, the calculated values of point load strength index of rock and ore samples based on uniaxial compressive strength are about 1.62 and 3.67 times of the test results.