Abstract: Defining the singular symmetric systems and singular state-space symmetric systems, their fixed polynomials are analyzed. The criterion for the existence of finite fixed modes of the singular systems with symmetric structure is investigated by analyzing the relation of inequality of matrix rank, and the relationship between uncontrollable and unobservable modes is obtained. A solution is thus given to the finite fixed modes. The results show that the finite fixed mode set in singular symmetric system is composed of all the finite uncontrollable and unobservable modes. Compared with the results known before, the proposed method is more effective and simpler.