In this study, we detected the surface defect and internal defects up to 0.3mm with accuracy of a relative discrepancy of 5% or less by using the arrival time difference of the reflected Rayleigh waves and the creeping wave. In the experiment, a Q-switched and pulsed Nd: YAG laser was used for the ultrasound generation while an optical fiber Fizeau interferometer was designed for detecting ultrasound generated by the laser line source. Our results showed that this system has a high sensitivity as well as a high spatial resolution comparing with other testing equipment.