Abstract: This study used 51-year-old Olea europaea plantation in Haikou Forest Farm of Kunming City, using water and fertilizer regulation treatment, Chlorophyll content (SPAD), net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), and water use efficiency (WUE) of leaves at initial flowering stage, full bloom stage, young fruit stage, and ripe fruit stage were compared and analyzed, and the correlation between P_n and fruit yield and quality was established. The results showed that the regulation of water and fertilizer significantly increased the SPAD, P_n and WUE of O. europaea during phenophase, and significantly increased the G_s at the initial flowering stage and the young fruit stage, but had little effect on the change trend of photosynthetic index of O. europaea during physiological period. The SPAD and P_n of O. europaea increased linearly during phenophase, the wavy curve of G_s decreased, increased and then decreased, the trend of T_r increased first and then decreased, and the WUE decreased first and then increased. In addition, P_n was positively correlated with saturated fatty acids and negatively correlated with linoleic acid content, but not with fruit yield, oil content and unsaturated fatty acids. From this, the regulation of water and fertilizer can improve the photosynthetic characteristics of O. europaea, but it does not affect the photosynthetic trend of O. europaea during phenophase. Reasonable water and fertilizer management is beneficial to the accumulation and promotion of saturated fatty acids in O. europaea fruit.