The mechanical effect and its characteristic produced by a high-power laser irradiated upon a solid target in water have been analyzed. An optical fiber pressure sensor basing on light beam deflection has been used to measure the pressure on the surface of the target,and the instantaneous pressure signals of laser plasma shock wave and bubble jetting have been gotten at different laser energy values. A compare has been made between the laser plasma shock wave and bubble jets after their coupling impulses have been calculated. The results have indicated that the bubble jetting is as important as the laser plasma shock wave,and more important sometimes.