With the increase of the railway load and running speed,the probabili ty of the rail screw hole defects increases and can cause serious damage to the rail operation safety.The traditional nonde structive testing (NDT) is not suitable for the rail development of testing needs nowadays,so we need to develop a new method to test the defects of the rail screw holes.The laser-electro magnetic acoustic (EMA) testing system of rail is designed based on the basic principles of the laser- EMA ultrasonic technique and the characteristics of the rail nondestructive testing.The comparison experiments ar e conducted by using the laser-EMA to test the screw hole,and the results show that the method can precisely find the upward ti lted cracks.From the laser-EMA signal processed based on wavelet threshold denoising,it could be seen that the signal to noise ratio is g reatly improved and all characteristics of the original signal are remained,thus the signal processed by the wavelet thres hold denoisi ng will be convenient for the damage identification and features extraction.Experimental results show that this method doesn′t n eed co upling medium and good surface conditions,and could realize non-contact,rapid scanning and precise inspection to the rail screw ho les.