Abstract: In view of problem that evaluation for operational reliability of power grid has large calculated amount, but requires short computing time, the paper proposed an evaluation algorithm for operational reliability of power grid based on distributed computing. The algorithm uses improved state selection and analysis solution to solve the relevance problem of random number sequence between computing terminals, effectively reduces communication traffic and improves computing speed. Evaluation software based on the algorithm has passed RTS-24 test system and actual operation test of a provincial power grid, and the test results show that the algorithm can effectively evaluate operational reliability of power grid, and the computing speed increases by a certain multiple with the increase of number of computing terminals.