Abstract: This paper deals with the problem of designing robust H∞ fault detection filter (FDF) for linear discrete time-varying systems with multiple measurement packet dropouts. By using an observer-based robust H∞-FDF as a residual generator, the design of FDF is formulated in the framework of H∞ filtering for a class of stochastic time-varying systems. A sufficient and necessary condition for the existence of the FDF is derived in terms of a Riccati equation. The determination of the parameter matrices of the filter is converted into a quadratic optimization problem, and the explicit solutions of the parameter matrices are obtained by solving the Riccati equation. Numerical examples are given to illustrate the effectiveness of the proposed method.