Abstract: In the autonomous control architecture for spacecraft, layered structure style is adopted. It manages all categorical applications through partition management to avoid interaction among them. This paper focuses on the partition schedulablity analysis and the partition design for fixed priorities scheduling model. It introduces a more exact partition task worst-case response time algorithm through observing the actually iterative operator, and addresses a partition designable condition based on the upper limit of the task utilization factor within the fixed priorities. By using the cost function, it also proposes the partition key parameters resolution model and a local optimal algorithm to implement the whole processor partition design. At last, it introduces a practical example to illustrate the validity of the analysis and design methodology.