The hazard-free utilization of sewage sludge has received extensive attention with the increasing production of this waste year by year. Proteins，polypeptides，amino acids and other nutrients in sludge can be effectively extracted using the method of thermal hydrolysis under alkaline condition to obtain alkaline thermal hydrolyzate(ATH). However，it is necessary to further explore the application of ATH in agriculture. In this study，6 different combinations of ATH and urea were applied to potted tomato to investigate the effect of the substitution of ATH for urea at different ratios on the yield，quality and nitrogen conversion. In the experiment，the quantity of nitrogen supplied by ATH was 0%(M0)，10%(M1)，20%(M2)，30%(M3)，40%(M4)and 60%(M6)of the total nitrogen amount applied in each treatment，respectively. The results showed that the fruit yield and single fruit weight in M3 treatment were the highest among all treatments，and increased by 17.88% and 15.19%，respectively，as compared with those in M0. The contents of reducing sugar，soluble sugar，organic acid，vitamin C，soluble solid content and sugar-acid ratio of tomatoes were significantly improved after the substitution of ATH for 20%–30% nitrogen supply. The results of technique for order preference by similarity to ideal solution(TOPSIS)analysis showed that the comprehensive performance of fruit yield and quality of tomato reached the optimal level when replacing 20%–30% of urea with ATH. The substitution of ATH for 20%-30% nitrogen supply was most beneficial to nitrogen，phosphorus and potassium uptake by tomato. The nitrate reductase activity of tomato leaves in M0 treatment was the highest[19.67 μmol/(g·h)]，followed by that in M2 treatment[13.61 μmol/(g·h)] . The glutamine synthase activity of tomato leaves in M2 was the highest[14.40 μmol/(g·h)]，followed by that in M3 treatment[14.38 μmol/(g·h)]，without significant difference between the two treatments. Rational application of sludge pyrolytic solution can promote the activity of nitrogen-converting enzymes in the crop，improve the yield and quality of tomato，and reduce the nitrate content of fruit.