The invention relates to a method for rapidly detecting the residual amount of polybrominated diphenyl ethers in shellfish. The method is characterized in that a capillary column (DB-5MS, 15m*0.25mm*0.10[mu]m) having a short column length and a thin liquid film is adopted and combined with gas chromatography-electron impact ionization/mass spectrography (GC-EI/MS) for detection. Novel grease cleaning powder (EMR-Lipid) is used in dispersive solid-phase extraction pre-treatment of polybrominated diphenyl ethers in shellfish for the first time. Through an improved QuEChERS technique, fat in a sample can be removed rapidly and in a large scale. The method is simple to operate and low in cost. 2) For a complex-matrix sample, a concentrated sulfuric acid oxidation cleaning technique is further combined to reduce interferences caused by a matrix and greatly increase the detection efficiency. 3) The capillary column (DB-5MS, 15m*0.25mm*0.10[mu]m) having the short column length and the thin liquid film is adopted and combined with gas chromatography-electron impact ionization/mass spectrography (GC-EI/MS) to achieve simultaneous rapid qualitative and quantitative analysis of polybrominated diphenyl ethers low and middle in bromination and polybrominated diphenyl ethers high in bromination in an aquatic product sample.