Abstract: Using a home-made multi-function preparation system of microarc oxidation coatings, the surface of TC4 titanium alloy substrate was treated in an electrolytic solution of Na₂CO₃ and Na₂SiO₃. SEM and XRD were employed to characterize the growth kinetics, surface morphology and phase component of the coatings fabricated at different treatment frequencies. The result shows that the growth rate of the coating is dependent on the treatment frequency. When the frequency is less than 2 000 Hz, the growth rate of the coating decreases sharply with the increase of the frequency, but it decreases slowly with the increase of the frequency in a range of 2 000~4 000 Hz, while the frequency is greater than 4 000 Hz, it keeps almost invariable with the increase of treating frequency. The coating surface is porous, with the treating frequency increasing, the roughness and micropore size of the coating surface decrease gradually, and the pore density increases gradually. The coatings consist of plentiful rutile and anatase phases and a small quantity of unsaturated oxide (TiO_2-x, 0.02＜x＜0.07). The relative content of rutile and anatase keeps invariable with the variation of the treating frequency, while the content of TiO_2-x in the coatings fabricated at a frequency less than 2 000 Hz is more than that fabricated at a frequency greater than 2 000 Hz.