Abstract: The composition, morphology and crystal structure change of surface oxides of TBF980 cold rolled continuous annealing steel before and after phosphating for different time intervals (0-90 s) were analyzed by carbon extraction replica technology combined with scanning electron microscope, transmission electron microscope and energy spectrum. The results show that the test steel surface oxides were mainly composed of thin film amorphous SiO_x and MnSiO₃ monocrystalline particles. With the extension of phosphating time interval, the amount of surface oxides decreased, and the content of silicon and manganese decreased significantly. However, when the phosphating film completely covered the surface of the test steel, there was still a layer of oxides between the phosphating film and the substrate. During phosphating, most of the amorphous SiO_x film was first broken and then rolled into balls, and separated from the test steel surface under the action of phosphating solution; a small part remained at the interface between the phosphating film and the substrate. Under the action of phosphating solution, the MnSiO₃ monocrystalline was first transformed into the composite particles of amorphous SiO_x and MnSiO₃ nanocrystalline, and then completely transformed into amorphous SiO_x.