Changjiu Shenshan limestone mine is the largest sand aggregate field in the world.The blasting fragmentation directly affects production efficiency of the mine.Combined with production practice, 11 blast tests were carried out in two mining areas where rock joints are developed.Based on Kuz-Ram blasting fragmentation prediction model, the average fragmentation after blasts was calculated.It is found that there is a great difference between the predicted value and the measured value.The results show that joint development degree and rock properties are the main factors affecting fragmentation distribution.The calculation of rock coefficient A in the modified Kuz-Ram model seriously affects the prediction results.It is suggested that the influence of rock density should not be considered in the calculating of the rock coefficient A.Through the analysis of data from four field verification blasting tests, it shows that the accuracy of the average fragmentation prediction value is significantly improved based on the Kuz-Ram model and the rock coefficient obtained by the proposed correction method.The relative errors are all below 10%, and the prediction accuracy is greatly improved.The research results can provide a technical support for the adjustment of blasting parameters in mining.