The energy transfer between PVK and TPB in PVK:TPB thin film in different concentrations was studied by emission spectra, excitation spectra, and absorption spectra. It is proved that the energy can be transfered from PVK to TPB in a wide concentration range and the transfer is most efficient at the concentration of 5% wt. A model Hamitonian based on a single chain model including the dopant was proposed to simulate the experiment. This model can be used to explain the experimental results very well.