Because the factor scores of the parallel factor analysis can represent the concentration of the various factors of every mixed sample, the method of parallel factor analysis can be used for source apportionment. But the factors were not the same as the source samples sometimes. In order to achieve source apportionment, a relationship between the mixed samples and the source samples of the three-dimensional fluorescence matrix was designed. The coefficients of the relationship came from the factor scores and represented the contribution ratio of the sources. The relationship can be used for source apportionment of pollutions in water environment. And the coefficients of the relationship represented the contribution ratio of pollutant sources.