The invention relates to a method for rapidly determining citric soluble phosphorus in a feed raw material, namely calcium hydrogen phosphate. The method comprises the following steps: (1) mixing a calcium hydrogen phosphate sample with a neutral ammonium citrate solution, maintaining the temperature at 63-67 for 0.5-1.5 hours, cooling to the room temperature, fixing the volume with water, uniformly shaking, and filtering, so as to obtain filtrate; and (2) carrying out determination by virtue of a colorimetric method, drawing a phosphorus standard working curve, acquiring the phosphorus content by virtue of the working curve, and calculating, so as to obtain the content of citric soluble phosphorus in the calcium hydrogen phosphate sample. Compared with the prior art, the method has the advantages that the safe and precise determination of citric soluble phosphorus in the feed raw material, namely calcium hydrogen phosphate can be realized within a short time, the operation is simple and convenient, the consumed time is short, the detection efficiency is high, a detection result is relatively stable, the repeatability is good, the errors are small, reference data can be provided for the purchasing and acceptance check of the feed raw material, and the quality safety of a feed is guaranteed.