In this work, we study the error limits of the network delay systems in terms of bandwidth and packet loss. The tracking error index of networked delay systems is identified by the tracking error energy. The error limits of the network delay systems are achieved by the spectral decomposition and partial decomposition techniques. The results of this work show that the tracking error limits are relevant to the inherent characteristics of the provided object (non‐minimum phase zero, time delay, and unstable pole). In addition, the packet loss, channel noise, and bandwidth also determine the error limits of the network delay systems. The simulation results show that the theory presented is valid.