Field experiments were conducted to study the effect of nitrogen and potassium fertilizer on yield and quality of processing tomato under drip irrigation with film mulch.Four nitrogen levels of 0，210，300，390 kg/hm2 and four K2O levels of 0，135，225，315 kg/hm2were adopted in this study.Processing tomato yield and quality were determined at mature stage.The results showed that both nitrogen and potassium fertilizers increased the processing tomato yield significantly,and effect of potassium fertilizer was inferior to that of nitrogen.Nitrogen and potassium fertilizers increased yield by 32.8%～51.4% and 13.3%～23.0%,respectively.Yield increase of processing tomato was mainly due to the promotion of fruit weight both by nitrogen or potassium fertilizers.The lycopene and soluble solids contents in 390 kg/hm2 nitrogen treatment were significantly lower than those in the 300 kg/hm2 treatment,which were 10.85% and 14.77%,respectively.Sugaracid ratio in 390 kg/hm2 nitrogen treatment was significantly less than that in the 210 kg/hm2 treatment,which was 36.04%. Lycopene increased with the increasing rate of potassium application.Lycopene content was the greatest in 315 kg/hm2 treatment.Soluble solids content and sugaracid ratio were improved 8.81%～13.73% and 3.98%～30.68% by potassium fertilizer application,respectively.Blossom end rot were decreased by potassium fertilizer application,but blossom end rot were increased significantly in excess nitrogen treatments. Parabola curves were fitted by the relation between tomato yield and N application rate or K2O application rate,and the N or K2O rate at the highest yield was 265.5 kg/hm2 and 268.5 kg/hm2,respectively.This study suggested that optimal range of N fertilizer application rate was 254.1～265.5 kg/hm2,and K2O was 225～230.2 kg/hm2.