调度策略是网络控制系统中的一个重要问题。本文分析了常见调度算法的基本特点，并根据热工自动控制系统的要求提出了一个基于紧急度指标（EI）的动态优先权调度算法，机理分析和仿真试验表明，此算法可以有效地提高总线利用率，保证系统的实时性，防止数据丢失。关键词网络控制系统调度算法现场总线Abstract Scheduling strategy is a very important issue in Network Control Systems（NCS）. This paper analyses the scheduling algorithms used widelyand their features. In addition，a new scheduling algorithm with dynamic priority based on Emergence Index（EI）is presented for automatic process control.Theoretical analysis and simulation show that by using this algorithm，the utilization ratio of the bus is enhanced effectively，the real-time performanceof the system is guaranteed，and data loss is prevented.Key words Network control system Scheduling algorithm Fieldbus