The work aims to improve the appearance and corrosion resistance of phosphating film by introducing ultrasound into the phosphating treatment of iron and steel parts. Firstly, the optimum formula of phosphating solution was determined by orthogonal experiment. Secondly, the effects of phosphating pH, phosphating temperature, phosphating time and ultrasonic power on the properties of phosphating film were investigated by single factor experiment. Finally, the morphology and phase composition of phosphating films prepared by ultrasonic phosphating and conventional phosphating were analyzed by scanning electron microscopy and X-ray diffraction. The optimum formula of phosphating solution obtained by orthogonal experiment included zinc oxide of 15 g/L, phosphoric acid of 90 g/L, hydroxylamine sulfate (HAS) of 10 g/L and manganese nitrate of 4 g/L. The order of influence of each factor on phosphating was phosphoric acid>manganese nitrate>zinc oxide>HAS. The optimum phosphating conditions were: pH value of phosphating solution of 2.3~2.6, phosphating temperature of 30 ℃, phosphating time of 45 min and phosphating ultrasonic power of 210 W. Under the optimum formulation and process conditions, the phosphating film had uniform and compact structure, and the dropping time of copper sulfate was 320 s. Compared with ordinary phosphating film, ultrasound phosphating film had a particle-to-particle ratio close to 1, while the ordinary phosphating film had a particle-to-particle ratio close to 4. The former had uniform and compact particle distribution, while the latter had uneven particle distribution on the surface of the film layer, with more pores among the particles. Phase composition of the former is mainly Zn3(PO4)2?4H2O and MnHPO4?3H2O. For the latter, the component Zn2Fe(PO4)2?4H2O was added to the phase composition. Ultrasound phosphating film has better appearance and corrosion resistance than the ordinary phosphating film.