To improve the performance of infrared dynamic scene target simulator,an infrared optical system based on TIR prism was developed. According to the principle of infrared target simulator based on DMD,relay optical subsystem based on TIR is used.Because of the limit of DMD rotation angle,a pair of optical prisms is used to separate incident light of illuminating system and reflected light of DMD according to total reflection theory and smallest angle space design.Due to the match of refractive-diffractive hybrid infrared imaging optical subsystem,optical system has the characteristics of compact structure and high transmittance.Through optical design simulation,the feasibility of optical system was verified.This infrared optical system has been applied to infrared target simulator successfully,and it meets the requirement of infrared target simulator.