Aiming at the phenomena such as heavy communication traffic and low fault tolerance of wide area protection, a wide-area backup protection algorithm is proposed based on regional multi information fusion. Firstly, the protection system is divided into several regions, and the fault area search is carried out according to the distribution characteristics of the fault current, which can reduce the communication traffic in wide area protection. Then, the protection action information of the fault area is normalized to calculate the basic probability assignment of the line fault evidence. Finally, the actual fault line is identified by the improved D-S evidence theory. An IEEE-39 bus model is constructed by PSCAD, the results show that the proposed algorithm can effectively recognize various types of faults, and has good performance of small wide area communication traffic and high fault tolerance.