The blasting of slope excavation results in the damage of rock mass consequentially. Through the statistic and analysis of rock core crack, sonic wave velocity test, microcosmic structure of core slice observation by electron microscope, core strength test to the sampled damaged slope rock mass, it indicates that the damage degree of smooth blasting to slope rock mass has no obvious relation with blasting scale but with the line density of explosive filling and the strength of the rock in damaged area decreases evidently.