The invention belongs to the technical field of glass fiber recycling and in particular relates to a method for processing a waste glass fiber filament powder material. The method comprises the following steps: firstly, performing soaking treatment on waste glass fiber filaments in a mixed liquid of an alkali and supernate of cement slurry, taking out the soaked waste glass fiber filaments, and performing washing, crushing, drying and powder milling, so as to obtain the waste glass fiber filament powder material. By adopting the method, an impregnating compound on surfaces of the waste glass fiber filaments can be removed, meanwhile, micro cracks on the surface of glass fiber can be increased, the strength of the glass fiber can be degraded, the brittleness of the glass fiber can be improved, and the powder milling effect of the waste glass fiber filaments when being processed into the powder material can be improved; by adopting the method, the waste glass fiber filaments can be efficiently powdered into the powder material, the powder material is uniform and stable in component, and can be mixed with other glass raw materials into a batch which can be fed into a kiln by using a reamer, so that the time and the labor can be saved, and the waste glass fiber filaments can be efficiently repeatedly used; and by adopting the method, the recycling treatment degree of the waste glass fiber filaments of the glass fiber industry can be increased, overstock of waste materials can be avoided, the market purchase cost of cement and alkali liquids is low, and large-scale treatment iseasy.