In view of the characteristics of the network system, such as the combination of software and hardware, multi-state, cross-platform, etc., the difficulty of building the test environment, the high test cost, and the difficulty in effectively carrying out the quantitative reliability evaluation, this paper proposes a quantitative reliability evaluation process and method of network system based on discrete event simulation combining software and hardware. According to the characteristics of the network system, a generalized network system reliability simulation evaluation process considering the combination of software and hardware is proposed. Taking two common network system reliability parameters, function availability and task reliability as examples, a generalized discrete event simulation-based network system reliability evaluation method and model are given. Finally, taking a communication system as the object, the simulation evaluation results of the system are given to Verify the feasibility and engineering applicability of the techniques and methods proposed in this paper.