In order to discuss the acceleration of energy exchange between fine structure energy levels of alkali atoms by buffer gas, the energy transfer process of fine structure collision in Cs(Rb)-N2 system were investigated experimentally by laser induced fluorescence spectroscopy. The fluorescence data of D1 and D2 lines of alkali atoms were obtained under different conditions. The experimental results show that N2 molecules are more involved in the acceleration of fine structure energy exchange in the Cs-N2 system, and the system has a high fluorescence conversion efficiency at 340K. In the Rb-N2 system, N2 molecules mainly participate in the quenching process, and the gain effect on the fine structure collision is not obvious. The results can provide reference data for the efficient operation of the semiconductor pumped alkali laser.