The invention relates to a method for detecting pig fat deposition by using phylaxin expression level, which comprises the following steps: 1) extracting total DNA from detected pig tissue, carrying out inverse transcription to obtain a cDNA sample; 2) carrying out PCR amplification on the cDNA sample from the step 1) by primer pair shown in SEQ ID NO:2 and 3 to obtain a gene fragment shown in SEQ ID NO:1; 3) carrying out PCR amplification on the housekeeping gene by primer pair shown in SEQ ID NO:5 and 6 to obtain a gene fragment shown in SEQ ID NO:4; 4) carrying out agarose gel electrophoresis on the PCR products from the step 2) and step 3), comparing the optical density value in a gel imaging system. According to the invention, the fat pigs and lean type pigs with 1 month age, 3 months age, 5 months age and 7 months age can be taken as detection objects, the expression level of fat cytokine phylaxin (resistin) can be detected, the protein level of resistin is taken for reflecting the deposition condition of the pig fat. The method of the invention has the advantages of rapidity, convenience, accuracy and no influence on normal growth of pigs, and is suitable for dynamically monitoring the fat deposition condition of pigs in the culture process.