The traditional in-orbit spacecraft monitoring system is based on centralized mode, with the problems of low timeliness and high professional requirements for on-duty personnel in the case of abnormal disposal. With the rapid increase in the number of spacecrafts in orbit, it is imperative to introduce mobile security technologies to support the secure access and rapid response of mobile terminals in a trusted network transmission environment, this pattern can also make an effective comprehensive utilization of online/offline spacecraft design and in-orbit management technologies. This article proposes a design scheme of in-orbit spacecraft monitoring system based on mobile terminal and cloud platform. Through the test of prototype system, it is verified that the spacecraft management experts can access to the back-end cloud platform and monitor the status of spacecrafts through the mobile terminal in a reliable way while being far away from the task center.