The quantitative analysis of the proportion of mixed source oil is of great significance to the determination of the contribution of oil source in different accumulation periods. In order to establish a fast and effective method to determine the contribution of mixed oil, micro-fluorescence spectroscopy was addressed to quantitatively determine relative contribution. Taking Wangjiagang area in the Dongying Depression as an example, biomarkers, including Gammacerane/C30Hoxane, Ts/(Tm+Ts), Ts/Tm and C2920S/(20S+20R), are used to fine classification of petroleum groups and oil source correlation of Es4 crude oil, and the type and maturity of crude oil are constrained. The mature(from well X1) and low-mature(from well X2) crude oil from the upper Es4 in the Dongying Depression were selected as two typical end members for mixing experiment. On the basis of verifying the reliability of components of the end member, the mass proportions of mixed oil(X1∶X2) are respectively 0∶10, 2∶8, 4∶6, 6∶4, 8∶2 and 10∶0. The relationships of maturity of mixed crude oil, contribution of end member and fluorescence spectrum parameters were analyzed. The results show that the fluorescence spectra of end-component are mainly three-peak type, and the mixed crude oil inherits the spectral spectrum shape features of end-component. The fluorescence color of mixed oil was obviously different. According to analysis of quantitative coefficient of fluorescence color(CIE-X, CIE-Y), the CIE chromaticity diagram shows nearly-linear changeof fluorescence color. With the increase of the amount of ES4 mature crude oil, the aromatic hydrocarbon content in the mixed oil decreased, and the fluorescence intensity also decreased, and the fluorescence color showed a significant blue shift. The fluorescence spectrum parameters(QF-535, fluorescence intensity at 567 nm, ratio of red to green, ratio of yellow to green) and the mixing proportion showed a good linear relationship, which could reflect the maturity of crude oil. As the maturity of mixed oil increases, the content of macromolecular hydrocarbons decreases, so the fluorescence spectrum parameters become small. The mathematical relation established by the mixing experiment can be used to identify the mixture ratio quantitatively, so as to determine the contribution of end member oil. This experiment can prove that these spectral parameters of fluorescence are effective to quantitatively characterize the contribution of end-member in mixed oil.