In this paper, the properties of fluorescence were studied of the thin films with different component ratios of polyvinyl carbazole(PVK)and Alq3. The energy transfer between PVK and Alq3 was studied through analysis of absorption spectra, excitated spectra, emission spectra of the thin films. When the content of Alq3 was high enough，the peak of Alq3 was quite evident in the abs orption spectra and excitated spectra, at the same time the emission spectra was the characteristic emission band of Alq3.When the content of PVK was high enough, the peak value of PVK is much greater than that of Alq3. At this time the extraordinary strong characteristic emission band of Alq3 and the feeble charac teristic emission band of PVK was observed. It is proved that the energy can transfer from PVK to Alq3 in a wide concentration range and it is most efficient at the concentration of 1∶7. A model Hamitonian based on single chain model including the dopant was put forward to simulate the experiment .This model can explain the experimental results very well.