Aimed at the characteristics of laser ultrasonic signal, based on LabVIEW virtual instrument technology, voltage signal of twowave mixing interferometer was acquired through the highspeed digitizer NI PCI5114. By using digital average method to improve the signal to noise ratio (SNR), finally wavelet denoising was carried out by using the wavelet function in MATLAB, and laser ultrasonic data acquisition and processing were designed, which had characteristics of simple and userfriendly interface. The testing experiments were done on X80 pipeline steel by using this system. The results show that the system can remove the noise interference in the signal, and implement detection of pipeline steel surface crack defect efficiently.