Abstract: Based on the continuity conditions at the interface on both sides, of which the pressures and velocities must be equal，the initial shock wave parameters of the medium surrounding a charge are given by calculating the equations valid for reflected wave in detonation products and the equations valid for shock wave in medium. Attenuation equation of stress waves, which is attenuated with increased distance of wave front from the vibration source, is extended from spherical charges to cylindrical charges based on the propagation theory of wave. Then the shock-wave parameters of the rock having the same distance from the detonation source are worked out in the case of decoupled charges and coupled charges. The conclusions obtained as follows: (1) the shock wave pressure is ten or hundred times larger than ultimate compressive strength of rock, then the smesh zone comes into being in the rock surrounding a charge；(2) in contrast with coupled charge blasting, decoupled charge blasting could decrease the initial shock wave pressure of bore wall’s rock, but increase the shockwave pressure of bore wall’s back rock. If the reasonable coefficient of decouple charge is adopted, the smesh zone will disappear and the dissipation of energy will decrease；(3) in view of a kind of nonlinear elastic medium, water, between detonation products and rock, can be suggested as an elastic buffer which increases the propagation of energy，protracts action time of shock wave and enlarges the action region of shock wave.

Key words: decouple charge, initial parameter, attenuation equation, elastic buffer