In order to explore the effect and approach of removing nitrate from soil under the combination optimization of different pH and carbon/nitrogen ratio (C/N) of organic materials, a 14 d reductive soil disinfestations (RSD) culture experiment was conducted on the greenhouse soil for 20 years continuous cropping. The effects of different pH and C/N of organic materials on NO₃^--N contents in soil and surface water and greenhouse gas emissions during RSD treatment were measured. The results showed that the change of pH had no significant effect on the removal of NO₃^--N in soil, and the contents of NO₃^--N in soil treated with pH 5, pH 7, pH 8 and pH 9 ranged from 41.94 to 44.33 mg/kg. The effects of different organic materials C/N on the removal of soil NO₃^--N were not decreasing, and the removal effect of soil NO₃^--N under C/N 60 treatment was the worst, and the emission of N₂O was the highest. The content of NH₄⁺-N in soil treated with C/N 90 was significantly higher than that under other treatment. The dynamic change trends of NH₄⁺-N and NO₃^--N contents and greenhouse gas emissions in soil and surface water under different treatments were consistent, but the NO₃^--N removal efficiency of the best C/N treatment of organic materials under different pH conditions was different. In summary, in low pH soil environment, high organic material C/N is conducive to soil NH₄⁺-N storage and NO₃^--N removal, and can take into account greenhouse gas emission reduction. After the pH is adjusted, the appropriate conversion of low organic material C/N is beneficial to reduce greenhouse gas emissions in the process of NO₃^--N removal.