Heavy rain and flood or their bad combination often occur in the Huaihe River Basin. To get the best comprehensive benefit of large reservoirs in period of heavy rain and flood, we adopted dynamic plan model in solving the join optimal decision making problem of the large clustered reservoirs in the Huaihe River Basin. Taking advantage of the home-grown huge computer Dawn1000's high speed and large storage, we solved the "dimension dissaster" and "grid disaster"in optimal calculation,gave the Join Optimal Decision Making Model of nine large reservoirs in the Huaihe River Basin, and can use them more efficiently.