There were differences in the selection of determination methods for the microbial biomass phosphorus content in acidic soils. The comparative analysis of the microbial biomass phosphorus content in acidic soils determined by different methods was not comprehensive, and there was a lack of basis for the selection of determination methods for the microbial biomass phosphorus content in acidic soils. In this study, the contents of microbial biomass phosphorus in acidic soil were determined using the sodium bicarbonate extraction method, the ammonium fluoride - hydrochloric acid extraction method, and the hydrochloric acid - sulfuric acid extraction method. The effects of these three methods on the determination of the microbial biomass phosphorus content in acidic soil were discussed to explore a suitable determination method for acidic soil. SThe results showed that the adsorption and fixation of inorganic phosphorus by acidic soil were strong, and the inorganic phosphorus in the soil was not fully extracted by the above - mentioned three methods. The average recoveries of inorganic phosphorus by the sodium bicarbonate extraction method, the hydrochloric acid - sulfuric acid extraction method, and the ammonium fluoride - hydrochloric acid extraction method were 21.62%, 27.39%, and 43.48%, respectively. The intensity of the adsorption and fixation of inorganic phosphorus by the soil showed a decreasing trend among the three methods. The sodium bicarbonate extraction method and the ammonium fluoride - hydrochloric acid extraction method were significantly affected by the adsorption and fixation of phosphorus by the soil. The increment of phosphorus in the sodium bicarbonate extraction method was small, while that in the ammonium fluoride - hydrochloric acid extraction method increased significantly. The hydrochloric acid-sulfuric acid extraction method was not significantly affected by the adsorption and fixation of phosphorus by the soil, and the phosphorus increment was equivalent to that of the ammonium fluoride - hydrochloric acid extraction method, demonstrating a good phosphorus extraction effect. The phosphorus extraction effects of the hydrochloric acid - sulfuric acid extraction method and the ammonium fluoride - hydrochloric acid extraction method were better than that of the sodium bicarbonate extraction method.There were significant differences in the determination results of the three methods (P < 0.05). The values of the measured microbial biomass phosphorus obtained by the sodium bicarbonate extraction method were significantly lower than those of the other two methods, and were not representative.There was a weak non - significant correlation between the results of the sodium bicarbonate extraction method and the ammonium fluoride - hydrochloric acid extraction method (r = 0.1122, P > 0.05), and there was a very significant positive correlation between the results of the sodium bicarbonate extraction method and the hydrochloric acid - sulfuric acid extraction method (r = 0.5281, P < 0.01). There was a non - significant positive correlation between the results of the ammonium fluoride - hydrochloric acid extraction method and the hydrochloric acid - sulfuric acid extraction method (r = 0.6690, P > 0.05).The color of the filtrate from the sodium bicarbonate extraction method increased the background value of the test solution, interfering with the detection. The coefficient of variation (CV) was 17.50%, and the precision was significantly lower than that of the other two methods. The filtrate of the ammonium fluoride - hydrochloric acid extraction method was likely to become turbid and needed to be treated in a cumbersome way before colorimetric detection. The CV was 8.81%, and the precision was good, but the applicable soil range was limited. The filtrate of the hydrochloric acid - sulfuric acid extraction method was clear for various types of acidic soil, with less detection interference. The CV was 8.76%, and the precision was good. The hydrochloric acid - sulfuric acid extraction method had a good phosphorus extraction effect, less detection interference, high method precision, and had obvious detection advantages over the other two methods for the determination of the microbial biomass phosphorus content in acidic soil.