The growth，photosynthesis and chlorophyll fluorescence parameters of oil peony were measured under 100% of full light (L0), 50% of full light (L1), 25% of full light (L2) and 15% of full light (L3), respectively. The results showed that: (1) the number of flowers, leaf dry mass per unit area (LMA) and stomatal density of L0 treatment were significantly higher than that of L2 and L3, but there was no significant difference with L1 treatment; With the increase of shading levels, the number of seed, stomatal area percentage decreased gradually and there was significant difference among treatments; (2) the photosynthetic rate (P_max), light compensation point (LCP) and light saturation point (LSP) decreased with the increase of shading; P_max and LSP of L0 treatment were significantly higher than that of L2 and L3, but there was no significant difference with L1 treatment; (3) the maximum quantum efficiency of photosynthetic system Ⅱ (F_v/F_m) of L3 treatment was 0.76, which was significantly lower than that of other treatments; With the increase of induction time by actinic light, the induction time by actinic light (F_v′/F_m′) decreased gradually and tended to be stable; the PSⅡ quantum yield efficiency (Φ_PSⅡ), photochemical quenching (qP) and non photochemical quenching (NPQ) increased gradually and tended to be stable. The order of F_v′/F_m′ and Φ_PSⅡ after stable was L0>L1>L2>L3, while NPQ was L3>L2>L1>L0, and there was no significant difference in qP among treatments. It is indicated that over shading (15%-25% of full light) severely inhibited the net photosynthetic rate of oil peony, and the number of flowers and seeds which directly related to the yield was also significantly decreased, resulting in a serious reduction in production. Therefore, 50%-100% of full light may be more suitable for the growth of oil peony in Kunming area, Yunnan.