Abstract: A field experiment was conducted under high-yielding conditions to evaluate the effect of nitrogen level on yield and sucrose synthesis of leaves in different types of peanut ( Baisha 1016 and Huayu 17). The result showed that the activity of sucrose synthesis and sucrose content of leaves increased with nitrogen within certain range. However, excessive nitrogen could decrease the activity of sucrose phosphate sythase and sucrose content of leaves. So applying proper nitrogen rate could be propitious to sucrose synthesis. Excessive nitrogen, however, could decrease economic coefficient, and thus decreasing pod yield. We could also increase pod yield by adding proper nitrogen to increase valid pods per plant and plumpness rate of pod. Different types of peanut had different responses to nitrogen, and the optimum nitrogen rate of var. vulgaris Harz in Arachis hypogaea was lower than common type peanut. The optimum nitrogen rate was about N 90kg/hm2 and N 135kg/hm2 for var. vulgaris Harz in Arachis hypogaea and common type peanut, respectively.