Abstract: The optimal hydroelectric operation model of cascade reservoirs during flooding periods is presented in this paper.The formulated model including river flood routing equations is the kind of dynamic programming model without Mar kovin property.Then,two new corresponding algorithms,simplified multi-dimen sional dynamic programming algorithm (MDDPA) and progressive optimal algorithm (POA) for dynamic programming models without Markovin property,are proposed.A case study is given.The result shows that these two methods are feasible,especially the latter has higher computing speed.