Abstract: The method of indirect fluorescence was developed to the determination of L-glutathione (GSH) in marine products. The protein in products was precipitated by TCA, then the pH of supernatant was adjusted to 10.5, during which the protein was precipitated again. OPA was used as derivatization agent to be mixed with extraction liquid (1∶1, v∶v) , which had been diluted, and then total fluorescence intensity (FIA) was determined at Ex 325nm and Em 400nm after reacting for 1 ²min in the dark. Meanwhile, FIB emitted by impurity was determined after using NEM to screen all the compounds with sulfydryl. FI emitted by GSH was known by deducting FIB from FIA, then GSH was determined indirectly. Its fluorescence intensity was linear to GSH concentration in the range of 0.125 ¹.250mg/L, R 2 =0.9963, regression equation was Y =57.012X. The GSH in three samples was determined with RSD ranged from 3.83%⁵.25% as well as average recovery ranged from 91.37% ¹02.20% . The poor specificity of fluorescence method was made up by the method of indirect fluorescence with higher precision which could be applied to the determination of GSH in marine products.