Effects of applying different nitrogen fertilizer on yield,quality and nitrate leaching in soil layer were studied during the cucumber growth period in greenhouse.The result showed that N uptake was not significant difference between conventional nitrogen treatment and optimum treatment.RE,PE and AE of conventional nitrogen treatment were lower than optimum treatment and 91.65% of applied N was lost by the kind of ways.Nitrate leaching loss was the dominant factor.It is also found that nitrogen applying with conventional treatment inhibited the absorption of other nutrients.In the term of yield and quality of cucumber,optimum treatment(N2) were not different from the conventional fertilizer treatment,but it could increase Vc content and active acidity(pH).