According to the characteristics of the terminal guidance phase of cruising missile,the scheme of common aperture IR/Ladar dual-mode imaging seeker system is proposed.The seeker system can precisely track and recognize the stationary and relocatable object on the ground.The seeker design scheme includes two imaging modes,the passive IR imaging mode and active pulse laser imaging mode.The passive infrared imaging mode is used for the coarse object search and acquisition and the active pulse laser imaging mode is used for precise object recognition and tracking.At the same time,the two imaging mode use the common optics.So the seeker system can not only meet the requirements of the large field of view for object search and acquisition,but also meet the requirements of high resolution for object recognition and tracking.