In the safety-critical system of spacecraft, memory management system is the essential part of operating system kernels to provide allocation and cleanup mechanism at the lowest level and is obviously critical to the reliability and safety of spacecraft computer systems. The memory management system should satisfy strict constraints such as real-time response, space usage limit, allocation efficiency and many boundary conditions. It has to use very complex data structures and algorithm to manage the whole memory space. In order to make the complex memory management system of spacecraft highly reliable, the formal verification of the system also becomes much more complicated as it embodies formal verification of complex data structures such as two level segregated double linked list with two level bitmaps, specification of operations, modeling on behavior, assertion definition of inner function, loop invariant definition and real-time verification. This paper provides an in-depth analysis on these problems and characteristics of spacecraft memory management system to find certain general method and theory based on hierarchical iteration for verifying a concrete operating system used on spacecraft. The results of this study offer potential benefits in improving the reliability of the spacecrafts of China.