This paper aims to achieve the prepared functional coatings containing a specific ratio of calcium and phosphorus, and guide the rational allocation of chemical reagents. On the medicinal titanium alloy surface the calcium biocoating and phosphorus biocoating were fabricated by micro arc oxidation (MAO) process. The coating morphology and elemental composition were observed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Wear resistant test on the coating surface was executed. The effect regulars of different concentrations and different molar ratio of electrolyte on the calcium and phosphorus content of medical TC4 alloy coating on micro arc oxidation system were researched, and the effects of electrolyte concentration on the molar ratio of calcium and phosphorus in the coating were also studied. The experimental results show that, with the increase of the electrolyte concentration, calcium content and phosphorus content in the coating are all decreased. But the ratio of calcium and phosphorus in the coating is increased, and the concentration of Ca/P molar ratio is higher, while calcium content and phosphorus content in coating are all lower. Wear resistant test shows that proper electrolyte concentration is helpful to improve the surface properties of coating. So if it wants to prepare one certain Ca/P molar ratio biocoating, the ratio can determine the different electrolyte concentrations of Ca/P molar ratio, and at last determine roughly the ratio of the compound reagent.