Abstract: In order to control the excavation contour of the underground powerhouse and reduce the damage to the retained rock mass, it′ s necessary to optimize the parameters of smooth blasting. The parameters of smooth blasting are obtained based on the theoretical calculation, and orthogonal experiments are conducted by taking borehole spacing, linear charge density and burden as the influencing factors of smooth blasting and taking half-hole ratio as the evaluation index. The optimal blasting parameters are obtained by visual analysis and variance analysis of orthogonal experiment. The field test results show that smooth excavation contour is realized and desired effect is obtained with the optimized blasting parameters.