Soil acidification is a key restricting factor to high and stable yields of crop.It also seriously affects the sustainable development of agriculture in China.In this paper,the effects of soil conditioner which mainly consisted of calcium carbonate on red soil pH,silica alumina ratio and vegetable yield and quality were studied through field experiments.The results showed that soil conditioner could significantly increase soil pH and silica alumina ratio,and could also improve water spinach yields and its quality.Compared with the control,soil pH was increased by 3.60%~21.65%,water spinach yield was increased by 5.81%~44.45%,vitamin C content was increased by 2.48%~23.97%,and soluble sugar content was increased by 4.18%~26.48% when the soil conditioner application concentration ranged from 600 to 1 800 kg/hm2.Meanwhile,the nitrate content of spinach had no significantly changes.It was found that the 1 500 kg/hm2 application amount was more reasonable.And,rotary tillage after surface fertilizer was a very reasonable and effective application method.