The invention relates to an epoxy resin electric power insulator casting molding method, which comprises a workbench, a fixing device, a first mold, a second mold and a moving device, and is characterized in that the fixing device comprises a placing groove, a driving motor, a circular rod, an annular plate, an annular clamping groove and a clamping frame; through cooperation of the workbench, the fixing device, the first mold, the second mold and the moving device, firstly, the first mold and the second mold of the epoxy resin electric power insulator needing to be subjected to casting molding are rapidly closed through the fixing device, so that traditional tedious mold closing and demolding are avoided, and the mechanical adaptability and working efficiency are improved; and the mold cavity is poured through the moving device, and the molten resin material can uniformly flow to the whole edge structure of the mold cavity through the matching of the fixing device, so that the qualified rate of the machine is improved.