This paper focuses on architecture suitable for largescale simulation system. Based on the scenario of large-scale internet simulation, the grid technology is introduced and a new architecture, GDSA is proposed. GDSA, a full grid-based architecture mainly focuses on four pending problems in distributed system: scalability, communications, management mechanism and QoS insurance computing environment. The Advantages of grid in scalability and uniform communication will be used to improve system's scalability and communication method. Management system will be built according to Meta-service mechanism. Contractual Computing Mechanism (CCM), a special mechanism added in GDSA, will provide QoS insurance for users. Three-layer QoS model, which is the core of CCM, will take charge of QoS problems in different levels. At the end, a prototype is designed and the experiment results based on this platform show that GDSA is a promising system to overcome the pending problems in distributed simulation.