Abstract: Using sensor failure models, the design problem of H∞ reliable controller for descriptor systems were studied. Firstly, common models of sensor failure of descriptor systems were constructed. In terms of these models, controllers based on observer were designed. Secondly, the definition of H∞ reliable controllers for descriptor systems was given. Thirdly, a sufficient condition that there exist H∞ reliable controllers was obtained when all sensors were operational in order as well as when some sensors failures happen. The sufficient condition is expressed by two generalized algebraic Riccati inequalities (GARI) with generalized constraints. These H∞ reliable controllers can make that closed-loop descriptor systems were admissible and H∞ performance. Meanwhile, these generalized constrains can be canceled by restricted system equivalent transformation for the descriptor systems such that these GAR1 with generalized constrains can be reduced. Therefore. these controllers can be designed by solving reduced two GARI. Finally, a numerical example is given to illustrate the design procedures and their effectiveness.