Influences of 2 water levels(W1: 4541.0,W2: 2270.6 m3/hm2) and 3 nitrogen levels(N1: 747.4,N2: 373.7,N3: 0 kg/hm2) reciprocally application on nitrate accumulation in tomato(Lycopersicon esculentum Mill,cv.Skala) fruit was studied from autumn tospring in solar greenhouse.Results showed that nitrate content in tomato fruit decreased along with its ripening process delaying and increased along with higher fruit setting position.Nitrate content in tomato fruit could be affected observably by irrigation and nitrogen supply levels.Nitrate content in tomato fruit increased with higher nitrogen supply under the same irrigation level and decreased with higher irrigation supply under the same nitrogen level.