In the current GB/T 27741-2018 “Paper and board-Determination of migratable fluorescent whitening agents (FWAs)” when extracting paper products, the residual lignin leached from cellulose which would interferespectral detection of FWAs. In this paper reported a tri-wavelength UV spectroscopy method for the determination of FWAs in paper products. By figuring out the isosbestic points shift at the range of 321～374 nm, the spectral interference of other species in the extraction solution on the FWAs measurement can be mathematically corrected. The results showed that the present method has the relative standard deviation of 3.7% and recovery of 99.1 and 107%, with the limit of the quantity of 19 mg·kg-1. Compared with the current FWAs detection method, the method has the advantages of simple analysis, easy operation of the instrument, and the like. Therefore, it is suitable for rapid and accurate determination of the content of migratable FWAs in various paper products, especially printing related materials and can guarantee the production quality control and market supervision of paper products.