A modular and integrated satellite dynamics simulation test system and method, the system is used for the ground simulation test of the small satellite attitude and orbit control system, the small satellite dynamics simulation test system is based on modular construction, including measurement and control upper computer and real-time lower computer . The measurement and control upper computer is a general-purpose computer, which runs the human-computer interaction software of the simulation system; the real-time lower computer includes the chassis, controller, digital signal acquisition and output card, analog signal acquisition and output card, RS‑422 communication card, CAN communication card, power supply Card, interface box, real-time lower computer except the chassis and interface box, all functional module boards are integrated based on the PXI bus, and the lower computer controller runs dynamics simulation calculation software. In addition to the interface box of the real-time lower computer, other modules are integrated inside the chassis. The upper computer and the lower computer are connected through Ethernet, and communicate based on the TCP/IP protocol, and carry out the interaction of operation instructions, collected data and simulation data. The present invention is applied to the simulation test of the attitude-orbit control system of the small satellite, which improves the integration and scalability of the small-satellite attitude-orbit control simulation test equipment, and the deployment of the equipment is simple and fast.