Abstract: Smooth blasting could bring good blast effect in the engineering of high-intensity and integrity rock mass. parameters design of smooth blasting by Conventional methods in general are difficult to get a better blasting effect in soft-fractured rock mass, Because existing a variety of weak structure surface and rock mass damaged by blasting. For this kind of rock, according to the blasting mechanism and characteristic of damage rock mass, the theoretical formula of smooth blasting parameters is put forward based on conjunct action theory of explosion shock wave and explosive gas-pressure. Validated by compare with common parameters and local explosion examination,the formula can apply to the soft-fractared rock mass.