Abstract: To explore the optimum amounts of top dressing for high yield and high efficiency of peanut, under field condition, we took‘Qinghua 7’as material to study the effects of top dressing by drip irrigation under mulch on photosynthetic characteristics and yield of peanut at pod-pin stage. The results showed that: the values of chlorophyll SPAD, the transpiration rate and the stomatal conductance of peanut leaves under different fertilizer application levels were significantly higher than those under non-fertilizer application, increasing with the increase of top dressing amounts at each growth stage, and the effects reached the maximum at T4, but there was no significant difference between T4, T2 and T3; the biological yield increased significantly with the increase of top dressing amounts; the pod yield, fruit number per plant, 100-pod weight, 100-kernel weight, and kernel rate all increased significantly at first with the increase of top dressing amounts, reaching the maximum at T2, then decreased with the increase of top dressing amounts. The results showed that top dressing with nitrogen, boron and calcium fertilizer could significantly improve the photosynthetic characteristics of peanut leaves, but the excessive amount of top dressing could result in excessive photosynthetic characteristics of leaves and overgrowth of aerial parts, which affected the formation and growth of peanut pods, and caused a decline in yield. The suitable top dressing amount was 60 kg/hm2 nitrogen, 15 kg/hm2 borax, and 45 kg/hm2 calcium oxide.