Abstract: The model of fluorescence lidar system for detecting marine oil was proposed and the fluorescence lidar equation was deduced. Based on the equation, the backscattering fluorescence signal from marine oil could be calculated. During the process of calculation, the oil extinction coefficient and fluorescence spectra conversion efficiency were introduced in the lidar equation. In order to obtain the SNR of lidar model, the special feature of background noise around marine oil was analyzed and the noise signal from yellow substance (CDOM) was calculated. As a result, the system SNR could be simulated. Simulation results indicate that hypothetical fluorescence lidar model could meet the demands for airborne detecting marine oil.