With the explosive growth and application of number of on orbit spacecraft, it is urgent to improve the parallel management ability and automatic and intelligent means of massive spacecraft. A cloud platform of spacecraft on orbit management based on knowledge and big data is designed and constructed. The feasibility of the system design is verified through practical engineering application, and the parallel management of more than 200 spacecraft on orbit is realized, which can provide reference for the efficient operation and management of complex constellation in China in the future.