The invention discloses a method for detecting miRNA (micro ribonucleic acid) in stomach juice, which comprises stomach juice extraction and neutralization, RNA release, chloroform extraction, isopropanol precipitation, ethanol washing, RNA reverse transcription, PCR (Polymerase Chain Reaction) detection and other steps. In the detection method, a sodium hydroxide solution is used to liquefy viscous components in the stomach juice, so that mucoproteins and polysaccharides are suspended in the solution, and the stomach juice is neutralized; trypsinase is added to carry out digestion, so that the mucoproteins and other proteins can be hydrolyzed, and cell components in the stomach juice are loosened at the same time, thereby facilitating centrifugal separation; and a Trizol solution is added to carry out repeated blow and beat, so that the RNA is completely released and separated from the polysaccharides, the mucoproteins and other impurities, thereby solving the problem that the RNA extraction can be disturbed by the acidity of the stomach juice as well as polysaccharides, mucoproteins and the like in the stomach juice. Thus, the invention can eliminate the disturbance caused by polysaccharides, proteins and other impurities in the stomach juice, complete the efficient extraction of miRNA in the stomach juice and carry out fluorescent quantitative PCR detection on the extracted miRNA.