The design problem of full order H_∞ filter for continuous singular system is addressed in this paper,in order to design satisfactory full order H_∞ filter with regular and impulse-free filter error dynamics.Lyapunov-Krasovskii functional and quadratic inequality method was used to get H_∞ time-delay criterion of filter error dynamics.A sufficient condition of robust H_∞ filter existence of singular system is provided.Finally,a numerical example is given to verify the effectiveness and practicability of the design method.