In order to detect the force of sheet-pile wharf stick,we adopt the dynamic testing technology to test the frequency of rod using the connection between the internal force and frequency of rod,and get the rod’s internal force.For a sheet pile wharf which has been running nearly 30 years and combining with the characteristics of the tie rod,we test the rod force.The test results show that the rod stress has a great influence on its frequency.So we can test the frequency of rod and deduce whether the rod is rusted off,and calculate the intact rod internal forces at the same time.