In the field of nondestructive evaluation, laser generation and detection of the surface acoustic waves (SAWs) are potentially useful for investigating material surfaces. SAW generated by laser line source is carried out on a kind of optical difference detection system based on optical beam deflection technique. The setup is simple and easy to adjust. Furthermore the system has advantages such as high efficiency of photo-electricity conversion, high frequency responding, the ability of ant-intervene and broadband detection etc.. It can be used not only to receive SAW, but also to detect surface-breaking defects in material. The experimental results verify that the SAWs generated by a line source have the advantages of powerful signal and good directivity. SAWs have been excited on sample aluminum with artificial surface-breaking defects. From the experiment, we attain the characters of reflected wave and transmitted wave by SAW interacted with the surface-breaking defects.