The full face excavation of hard rock tunnel has high requirements for controlling the volume of cutting cavity,the smoothness of tunnel face and the under-excavation of bottom.Based on the full face excavation of class Ⅲ hard rock of Zhaishan tunnel,the optimization blasting parameters of cutting holes was put forward by using the methods of field test,problem analysis and empirical formula.From the perspective of expanding the volume of cutting cavity,four pairs of compound-term short cutting holes were added in the main cutting area from top to bottom,the depth of the long cutting holes was expanded to 3.8 m,and the distances between the bottom of the compound-term long and short cutting holes were reduced to 0.3 m.Considering powder factor of rock blasting and rock breaking volume,the maximum single hole charge of the long cutting holes was determined to be 3.0kg.The results show that after blasting excavation,the hard rock face is smooth,the bottom is flat and the sizes of rocks are reasonable by using the optimized cutting parameters.The powder factor of the overall cutting blasting is decreased by about 4.5%.