To implement the integral optimization of satellite engineering, a upper-stage spacecraft is proposed based on the combination of a small satellite and a small launcher, and a reconfigurable integrated electronic system for the upper-stage spacecraft is designed to achieve the high function density development of aerospace electronic systems. By taking the Microblaze as a soft-core processor, the electronic system improves its expandability based on a distributed network structure with CAN bus. It realizes the time sharing of a central computer in the core of electronic system and satisfies different requirements of the launching phase and on-orbit phase. Furthermore, the control algorithm has implemented by hardware, which reduces the calculation of processor and improves the computing and processing capabilities of the system. A semi-physical system is built and the full-mode simulation is carried out to verify effectiveness of the designed system. The experiment results show that the control period in the launching phase is 10 ms, the running time of control algorithm is about 7.5 ms, and the attitude orientation accuracy and the stability are 0.035°and 0.000 68(°)/s, respectively. The reconfigurable integrated electronic system can achieve the full-mode flight mission of upper-stage spacecrafts, satisfy the requirements of strong real time in the launching phase, high stability in the on-orbit phase and can offer higher control accuracy.