Abstract: The matched filter made in advance is the key for good correlation recognition results in Vander Lugt correlator. The data utilization ratio of detour phase encoding method which is always used is low, and its correlation results need to be improved. Mapping encoding method based on the minimum Euclidean distance principle was studied, the filters were encoded by amplitude and phase modulation characteristic of the spatial light modulator, then the effect on the correlation results of the amplitude factors for matched filtering function was analyzed by emulating experiments, and finally the correlation results of two methods were contrasted. Simulation results indicate that the more the amplitude factor is, the higher the correlation peak is; while the amplitude factor reaches 103, the correlation peak reaches its maximal value; and at the time the correlation peak is nearly two times as much as that of detour phase encoding method. Consequently the mapping encoding method is more propitious for the differentiation of correlation peaks than detour phase encoding method.