Abstract: Based on a quadratic separator, a robust reliable filter design method for a class of systems with polytopic type uncertainty is presented against sensor failures. By making use of interpretation of system robust stabilization from the topological separation viewpoint, the matrix meaning plant can be decoupled from the matrix expressing faults via the quadratic separator, and a satisfactory robust reliable filter, which is less sensitive to the sensor failures, can be obtained. In order to reduce the design conservativeness, a condition for the existence of a parameter-dependent separator is proposed, and further the filter design can be converted into the optimization problem involving linear matrix inequalities (LMIs). An example is given to illustrate the effectiveness of the proposed method.