Abstract:The block of breakwater protection surface is an important component of breakwater to resist wave impact. The angular velocity signal obtained by IMU inertial sensor was processed to an IMU inertial sensor are used to measure the wave-induced effect on the protecting surface block. Based on the principle of coordinate system transformation in inertial navigation system, the IMU inertial sensor was mounted on the protecting surface block and placed in three different water line positions for testing, btain impact velocity and collision number. The results show that the collision number is larger at z/Dn =-2 than at z/Dn = 0 and z/Dn=2, and the maximum impact velocity occurs at z/Dn=0. The above measurement parameters can provide quantitative evaluation for block protection.