The effects of urea and nitrification inhibitor 3,4-dimethylpyrazole phosphate(DMPP)combined application on nitrogen transformation in gravel soil and photosynthesis of grape leaves were studied in Xinjiang，in order to provide theoretical basis for the scientific application of DMPP.The grape variety Cabernet Sauvignon was used as the experimental crop，and six treatments were set up，including no fertilizer，urea alone，adding 0.5%，1%，3%，5% DMPP(0.5%，1%，3%，5% of nitrogen content)to urea，respectively.The effects of different concentrations of DMPP and urea on soil NH4+-N，NO^3--N，nitrification inhibition rate，pH value，leaf SPAD value，net photosynthetic rate and intercellular CO₂ concentration were studied.The results showed that the content of NH4+-N in soil increased by more than 150 mg/kg when urea was applied，and the decreasing trend of NH4+-N was delayed when DMPP was added at different concentrations compared with urea alone，the increase of NO^3--N in soil could be reduced effectively，but DMPP had no obvious dose effect in the range of 0.5%-5%，and the effect of adding 1% DMPP was the most significant.The nitrification inhibition rate of different concentrations of DMPP was different，the inhibition rate of 1% DMPP was 49.60% on the 14th d，compared with the control group，the application of urea significantly increased the net photosynthetic rate and SPAD value of leaves. The 4 principal components extracted by principal component analysis covered 84.146% of the original information，of which 1%DMPP had the highest score.In conclusion，the mixed application of urea and DMPP can significantly inhibit the conversion of NH4+-N to NO^3--N，increase the nitrification inhibition rate，decrease the apparent nitrification rate，and maintain a high level of NH4+-N content in soil，at the same time，the net photosynthetic rate was increased significantly.Considering the economic benefit and application effect，1% DMPP combined with urea is the best in sandy gravel soil of Xinjiang.