Abstract: In order to solve the technical problems of the test of existing pile foundations, a new nondestructive testing technology—— Pile Sonic Testing(PST)technology was proposed. PST technology and its characteristics were explained in detail by covering its basic principles, numerical simulation, field collection, data processing and engineering interpretation of results was explained. In order to verify the accuracy of this method,the PST method was used to test the pile length and completeness of the existing pile foundation.The test results show that the PST detection technology has high detection accuracy for existing pile foundations, and it provides a reliable detection technology for the detection of existing pile foundations.