The invention discloses a space-based modular aircraft for conducting decentralized deployment on a micro-nano load and an orbital transfer guidance method of the modular aircraft. The aircraft comprises a bearing and thrusting integrated unit, a measuring and control integrated unit and a light-small interstage adaptation and separation device; orbital transfer to a target rail can be achieved remotely, autonomously and rapidly. By means of the space-based modular aircraft and the orbital transfer guidance method, the problems of high integration of the aircraft, space based bearing and separation, space-based rapid mobility and deployment and modular separation are solved, and the requirement for rapid deployment of the micro-nano load is achieved.