The invention relates to a micro-arc oxidation electrolyte system added with calcium lactate. The micro-arc oxidation electrolyte comprises an acid containing phosphorus or a phosphate and the calcium lactate, wherein the ratio of Ca to P is smaller than or equal to 1/2. Constant positive voltage and negative voltage are adopted, through a micro-arc oxidation technology, a calcium-phosphorus film layer is prepared on the surface of self-casting Mg-2Sr alloy, XRD and FT-IR infrared test result shows that phases contained in a micro-arc oxidation film layer before being soaked in a simulated body fluid mainly are Mg, MgO, Sr2Mg17, MgF2, CaO, CaF2, Ca3(PO4)2(TCP) and the like, and, in addition, existing of new phases, such as Ca2P2O7, Mg(OH)2, HA, Sr-HA, are further detected in the film layer after being soaked. According to the micro-arc oxidation electrolyte system added with the calcium lactate, the micro-arc oxidation film layer prepared by adopting the method has a typical micro-pore structure, and moreover an obvious micro crack is not discovered; and the contents of calcium and phosphorus phases in particle-shaped corrosion products on the surface of the micro-oxidation film layer are high, and the biological performance (the biocompatibility or the bioactivity) is good. Compared with a base body, the micro-arc oxidation film layer has good corrosion resistance, and the corrosion current is enhanced by more than two orders of magnitude compared with an existing high-calcium and low-phosphorus electrolyte.