Aqueous CdS@ZnS core-shell quantum dots（QDs） and water-based polyurethane（PU）were prepared by ion co-deposition method and one-pot method, respectively. After the QDs and PU were uniformly mixed at the mass ratio of 1:1, they were dropped on substrates with different surface tensions in order to form QDs/PU composite film after natural drying. The studies show that the surface tension of the substrate can directly affect the fluorescence properties of QDs and QDs/PU films. In this paper, the surface tension of the substrate was characterized by measuring the contact angle. The larger the contact angle is, the smaller the surface tension is. When the surface tension is large, it will cause a large-scale aggregation of QDs, resulting in an excessive concentration of regional QDs, and causing the concentration to be quenched. Although the increase of the surface tension of the substrate can improve the color purity of the quantum dots, it will also lead to a decrease in its fluorescence intensity. Under the 365 nm of UV lamp, it can be clearly seen that the fluorescence intensity of the interface between the substrate and the quantum dot dispersion is significantly higher than that of other areas. The QDs/PU composite film was tested by fluorescence spectrometer, and it is found that the fluorescence intensity of the composite films also decreases with the increase of surface tension.