X-ray dual-energy computed tomography imaging technique is an important material detection and recognition method in the field of security inspection. The projection decomposition is the nuclear content and key technique in the pre-reconstruction algorithm of dual-energy computed tomography. According to the disadvantages of the current algorithms, a projection decomposition algorithm based on projection matching is proposed. Firstly, based on energy spectrum of the system and the linear attenuation coefficient curve of the basic materials, the high-and low-energy projection lookup table can be got by solving the projection integral equations set. For a given dual-energy projection, find the best match point in the lookup table and then obtain the decomposition projection of basic materials. The proposed algorithm avoids the process of complex iteration and optimization and simplifies the process of system calibration. The decomposition accuracy depends on the step setting of lookup table. Compared to the current algorithms, the proposed algorithm′s realization is more simple and easy for parallel computation. The feasibility of the algorithm is validated by the results of simulation experiment.