The invention discloses a magnesium alloy microarc oxidation method for conditioning a film structure based on enhanced CO2 gassing induced by a carbonate additive, relating to a microarc oxidation method. The magnesium alloy microarc oxidation method for conditioning the film structure based on enhanced CO2 gassing induced by the carbonate additive, provided by the invention, can be used for generating CO2 gas in an anode area and conditioning the film surface structure. The method comprises the steps of: preparing microarc oxidation treating fluid; 2, cleaning the surface of magnesium alloy for removing oil; 3, washing with water; 4, performing microarc oxidation treatment; and 4, drying to obtain the microarc oxidation ceramic film. In the invention, CO2 is gassed out at the same time when O2 is gassed out, and the CO2 is decomposed and escapes on the surface of a film to form certain pores, so that the purpose of regulating the porosity of the film is achieved and the film structure is further regulated. The magnesium alloy microarc oxidation method is applied to the technical field of material surface treatment.