Fault diagnosis is the premise of the self-healing of smart grid in the future. In order to promote the efficiency and accuracy of the fault diagnosis system，this paper puts forward a new kind of power grid fault diagnosis framework. It is supported by data grid and its main skeleton is the distributed system. Data grid provides reliable data to the fault diagnosis system in time while the distributed computation supplied by the distributed system can enhance the execution speed of the fault diagnosis program. The new diagnosis system including the data grid and distributed computation is obviously superior to the traditional C/S structure. Finally，the validity and feasibility of this method are testified by examples.