Abstract: Taking ‘Jiamei No.8’ tomato as test material, five treatments were set up in the greenhouse, namely CK（no nitrogen fertilizer）,U treatment（normal urea combined with water-soluble fertilizer）,CRU treatment（controlled release nitrogen fertilizer combined with water-soluble fertilizer）,-20%CRU treatment（controlled release nitrogen fertilizer reduced nitrogen by 20% combined with water-soluble fertilizer）,-40% CRU treatment（controlled release nitrogen fertilizer reduced nitrogen by 40% combined with water-soluble fertilizer）.The LI-8100 A carbon flux measurement system was used to measure the soil respiration of the greenhouse tomato.The effects of controlled release nitrogen fertilizer and nitrogen reduction on soil respiration in greenhouse vegetable fields were studied.In order to provide a reference for reducing the application of controlled release nitrogen fertilizer to increase tomato yield and reduce soil respiration rate.The results showed that the peak soil respiration rate of each treatment in the tomato growing season appeared in 10-15 days after planting and 5 days after topdressing.Both the controlled release nitrogen fertilizer and nitrogen reduction treatments reduced the peak soil respiration rate, and with the extension growth period, the peak soil respiration rate showed a gradually decreasing trend.The cumulative emissions of soil carbon were showed U＞CRU＞-20%CRU＞-40%CRU＞CK.Compared with U treatment, the cumulative emissions of soil carbon from CRU,-20%CRU and-40%CRU treatments were reduced by 21.88%,27.54% and 31.51%,respectively.Compared with U treatment, the output of CRU and-20% CRU treatment was increased by 10.57% and 8.14%,respectively.Correlation analysis results showed that soil moisture, ammonium nitrogen（NH⁺₄-N）,nitrate nitrogen（NO^-₃-N）,pH and soil respiration rate had extremely significant correlations, microbial biomass carbon and nitrogen, cellobiohydrolase, β-1,4-xylosidase, β-1,4-N-acetylglucosaminid and α-glucosidase had extremely significant or significant correlations with soil respiration.