NOVELTY - Preparing electrolyte of all solid state nano-composite polymers comprises (1) dissolving polyethylene oxide and polyurethane in an organic solvent; stirring to evenness and then placing in an oven to achieve compatibility by heating; (b) adding iodized salt and iodine to the mixture of polymers obtained in step (a) then stirring to evenness; (c) adding the nano-material to the mixture obtained in step (b) then symmetrically dispersing; (d) pouring the mixture obtained in step (c) into a die to volatilize the organic solvent and then placing in a vacuum oven to dry.    USE - The method is useful for preparing electrolyte of all solid state nano-composite polymers for dye-sensitized solar cell (claimed). The method is useful for the preparation of polymer electrolyte. The electrolyte of all solid state nano-composite polymers is useful for dye-sensitized solar cell and lithium cell.    ADVANTAGE - The method provides some advantages to the polymer electrolyte such as high room temperature ionic conductivity and strong interface infiltration capacity. According to the method, crystallization at room temperature of the polyethylene oxide is prevented and the interface infiltration capacity and cohesive property of the polymer electrolyte are improved. The materials used in the method are easy to be obtained and its operation is simple and easy.    DETAILED DESCRIPTION - Preparing electrolyte of all solid state nano-composite polymers comprises (1) dissolving polyethylene oxide and polyurethane in an organic solvent based on a mass ratio of 9:1-1:9; stirring to evenness and then placing in an oven to achieve compatibility by heating; (b) adding iodized salt and iodine to the mixture of polymers obtained in step (a) then stirring to evenness, where the content for total quantity of the iodized salt and iodine within the polymer electrolyte is 20-40 wt.% and the mole ratio between the iodized salt and iodine is 10:1-20:1; (c) adding the nano-material to the mixture obtained in step (b) then symmetrically dispersing, where the content of the nano-material within the polymer electrolyte is 0-15 wt.%; (d) pouring the mixture obtained in step (c) into a die to volatilize the organic solvent and then placing in a vacuum oven to dry to ensure that the organic solvent is drained-off completely.