The invention provides a method for preparing industrial use trisodium phosphate from glyphosate production waste materials by a one-step method. The method comprises the following steps of (a) providing phosphorus containing waste materials, wherein the phosphorus containing waste materials are glyphosate production waste materials, wherein the TP content is 2 to 40 weight percent; the COD content is 5 to 50 weight percent; (b) after caustic soda liquid or caustic soda flakes are added into the phosphorus containing waste materials, reaction is performed at 600 to 900 DEG C; the industrial use trisodium phosphate is performed. By using the preparation method, the goal of preparing the industrial use trisodium phosphate product by the one-step method can be realized; the preparation methodis relatively simple and convenient; the product has high purity.