Abstract: Network communication delay will influence the control performance of traditional PID control algorithm in networked control systems(NCSs).A cost function is used as the criterion of performance evaluation and simulation is made to analyze the effect of all sorts of network delays on the PID control performance.With root locus method,the influences of network delay and PID parameters on the control system stability and control performance are analyzed,and a NetCon controller is used to control an experiment system under different network delays.The experiment results demonstrate the validity and effectiveness of the simulation analysis.