This paper is concerned with the problem of H-infinity filtering for network-based systems with time-varying delay via delta operator approach. The main work is to design a filter such that the filtering process exponentially stable and the transfer function meets a given H-infinity norm upper bound constraint for all admissible uncertainties. A network-based model with time-varying delay is proposed via delta operator approach. The performance analysis of H-infinity filtering-error systems are proposed by retaining some useful time-delay terms. Sufficient conditions of exponentially stability for filtering error system are derived in terms of linear matrix inequalities, and the explicit expression of the desired H-infinity filter is also obtained. A numerical simulation shows the effectiveness of the proposed method.