Abstract: Using eddy covariance flux data observed in the field during the growing season of oilseed rape（September 2020 to May 2021）, the dynamic characteristics of ecosystem light use efficiency(LUE_eco) and apparent initial quantum efficiency（α） of oilseed rape and the relationship between them were analyzed, and environmental factors and vegetation indices were combined to explore the relationship between LUE_ecoand each parameter. The results showed that the daily variation of LUE_ecoof oilseed rape showed a U-shaped curve change, higher in the morning and lower in the afternoon, and the difference among different months was mainly reflected in the height of the curve change; the monthly variation of LUE_ecoof oilseed rape roughly showed a parabolic change of first increasing and then decreasing, which was consistent with the monthly variation of α; there was a significant linear positive correlation between the light use efficiency rates obtained by different calculation methods, and the overall LUE_ecowas about one-half of α. On the seasonal scale, LUE_eco showed a partial peak curve variation in general, with a mean value of 0.034 7 μmol（CO₂） · μmol（PAR）-1for the whole growing season; the seasonal variation of LUE_ecowas mainly influenced by photosynthetic effective radiation, air temperature and crop growth. The results could provide some reference for exploring the variability characteristics of light energy utilization and the simulation study of ecosystem productivity based on light use efficiency model.