Abstract: Boron phosphate（BPO4） was prepared with boric acid and monoammonium phosphate as raw materials by solid state reaction method.Influences of the amount-of-substance ratio of boric oxide to phosphorus pentoxide and reaction temperature on the product′s composition and structure were investigated.Optimum technological conditions were determined as follows：the amount-of-substance ratio of boric oxide to phosphorus pentoxide was 1.0～1.05，and the reaction temperature was 850～1 000 ℃.The phase structure of the product was analyzed by IR and XRD.Temperature was the main factor affecting the phase structure，when the solid state reaction temperature reached 1 000 ℃，the product had such characteristics as complete crystal structure and stable product quality.The reaction process was studied by TG-DTA and DSC analysis and reaction mechanism was brought forward.Finally，it was confirmed that the synthesis technique was technically feasible and economically reasonable.

Key words: boron phosphate, solid state reaction, synthesis techniques