本文着重叙述了呼叫模拟与测试系统的设计思想，它采用面向对象，ＳＤＬ代码动态加载和ＳＤＬ代码存储区的共享技术，使系统具有模块独立性强、接口规范和模拟功能容易扩展的特征。利用实时系统任务抢占式调度策略实现“时间冻结”，确保模拟的实时性，在无话路硬设备情况下，对各呼叫类型进行模拟。该设计方案已成功应用于国产６万门大容量程控交换机的产品研制中，为程控交换机功能和服务性能指标的测试提供了新的模式。 This paper focuses on the design of call simulation and test system. It adopts object-oriented, SDL code dynamic loading and SDL code storage area sharing technology, which makes the system have the characteristics of strong independence of module and easy expansion of interface specification and simulation function. Utilize preemptive scheduling strategy of real-time system tasks to achieve “time freeze” to ensure real-time simulation, and simulate each call type in case of no hard-device. The design scheme has been successfully applied to the domestically produced 60,000 high-capacity program-controlled switches in the product development, program-controlled switches and service performance indicators for the test provides a new model.