A method based on pixel-based fusion method was proposed for infrared dual-band target simulator. The dual-band subwavelength grating instead of optical thin film was used as a filter, only a set of scene generator and projection system was used to complete the dual-band infrared target simulation. This method solved the traditional dual band infrared target simulator′s problem of relatively complex structure, high cost and untunable energy ratio. Firstly, the working principle of the method was introduced and its feasibility was illustrated. Then, based on the rigorous coupled-wave theory, subwavelength grating filter′s characteristics under different parameters were analyzed. Finally, the design of grating was completed according to the dual wavelength detection needs.