Abstract: This paper presents an improved analysis and synthesis approach for networked control systems (NCSs) with non-ideal network quality of services, such as time-varying network-induced delay and data dropout. Following the existing model of NCSs and introducing the logic zero-order holder (ZOH) to choose the newest controller signal, we employ the free weighting matrices to deal with cross product items, and utilize the convexity of the matrix function in our derivation to obtain less conservative results. Numerical examples are provided to show the effectiveness of our proposed method.