In this paper, a new and noncontact ultrasonic testing method with using laser grating is proposed for residual strain measurement. In this method, the laser grating technique is utilized to generate coherent surface waves with a specific wavelength in narrow frequency band. A numerical method based on finite element model is established to simulate the coherent surface waves generated by the laser grating in pre-strained media to determine the capability and sensitivity of this method. The relationship between the strain and frequency spectrum of the coherent surface wave is studied. Finally, an experiment validation of the laser grating based UT of residual strain is carried out with using specimen with different plastic strain by tensile test.