The measurement technology of line structured light vision is utilized for the rail wear measurement due to its noncontact and high precision features. The measurement of rail full profile and field calibration of line structured light visual measurement system are two typical problems. To enhance its performance, a binocular calibration method of line structured light based on free plane targets is proposed for field application. Firstly, the vision measurement system is established based on line structured light binocular visual measurement model. The chessboard images containing line structured light and the chessboard images without line structured light at any positions in the public viewing angle of both sides of the camera are collected respectively. Then, the internal parameters of both sides of the camera are obtained by using the chessboard plane calibration method. The feature points which are generated by intersection of line structured light plane and target plane at different positions are used to fit the planar equations of the line structured light plane in both sides of the camera coordinate system. According to the Rodriguez transform principle, the external parameters between the line structured light plane and two cameras are solved. Finally, the internal parameters and the external parameters are utilized to realize the measurement of rail full profile. The field test is also carried out. Experimental results show that the calibration error of the cameras is about 003 pixels, the fitting degree of line structured light plane is 0999, and the total measurement error of rail profile data is 054mm, which meets the requirement of measurement accuracy.