In order to meet the practical requirement of EMCCD investigation and detection device, a three-field-of-view(FOV) optical system was designed．The electron multiplying charged coupled device (EMCCD) was used for receiving, and the size of the image pixel was 16 m16 m．By comparing the advantages and disadvantages of 4 different imaging structures, the initial structure of three-FOV optical system was chosen. Furthermore,the system was optimized by using CODEV software to guarantee the excellent image quality of the three-FOV optical system in the wavebands from 600 nm to 850 nm. The design results show that the MTF of three-FOV optical system is larger than 0.5 at 35 lp/mm, the size of the root-mean-square(RMS) spot is less than the size of the pixel, the distortion is less than 0.2%, and the image contrast satisfies the use requirement well.