An improved calibration method were proposed to avoid the shortcoming that it has a huge nonlinear relationship between system input and output when using laser triangulation under large range small anger circumstance. Comparison among several typical calibration methods was firstly presented, by which the advantages and disadvantages of each method were considered. A compound calibration method which has the potential of high precision and stability were then proposed. A displacement measuring system was completed based on this method, which was examined by experiments to have obvious superiority over those systems based on typical method when used in huge arrangement measuring.