Molecular fluorescence spectrometry and gas chromatography were applied to study the form of organic phosphorus in protein matrix of aquatic products. The influence of proteins on extraction of organic phosphorus from aquatic products samples was also discussed. The results showed that there was a strong binding effect between organic phosphorus and proteins. In the volume fraction of acetonitrile (ACN) between 70% and 90% aqueous solution protein denaturation could occur and the organic phosphorus binding with the protein could be released, which resulted in a higher recovery rate of the extraction of organic phosphorus from protein matrix samples. The method involved the following steps: extracted the fish sample by using the solution of V(acetonitrile)∶V(acetic acid)∶V(water)＝90∶1∶9, eliminated the moisture by adding anhydrous magnesium sulfate (MgSO₄) plus sodium acetate (NaAc), purified the samples by using primary secondary amine (PSA) and GDX-103. The extract was then centrifuged and transferred to vials for direct analysis by gas chromatography (GC). The method was used to the determination of five organic phosphorus residues (dichlorvos, methamidophos, dimethoate, methyl-parathion and ethyl-parathion) in fish. The recovery ranges and the detection limits were 72.97%～107.21% and 0.002～0.045 mg•kg^－1, respectively. The method was simple, quick and sensitive.

Key words: protein, binding effect, organic phosphorus, matrix eliminating, gas chromatography, aquatic product, direct analysis