Study on modified sandy loam soil and increased tomato yield by using biochar was conducted through the pot experiment. There were five installed treatments that sandy loam soil (CK), per kilogram sandy loam soil plus 10g of biochar(C10), per kilogram sandy loam soil plus 20g biochar(C20), per kilogram sandy loam soil plus 40g of biochar(C40) ,and per kilogram sandy loam soil plus 60g of biochar(C60).Results show that biochar can improve soil fertility and the effect of higher biochar application is remarkable. Compared with CK, the content of organic matter in treatment C60 increased by 560%. In treatments C60 and C40, both available N increases by 290% and 150% respectively; both available P increases by 410% and 290%, and both available K increases by 290% and 150% respectively. Soil water content in treatment C60 is 170% higher than CK. Using biochar can effectively improve tomato yield. Comparing with CK treatment, tomato yield increases 98% and 170% in treatments C60 and C40, respectively, and the largest increase is in treatment C40.Through correlation analysis, water and fertilizer are important factors affecting tomato yield, and correlation is more than 80%. In order to make full use of existing resources, reduce the use of chemical fertilizers, save water resources, improve agricultural land, water and ecological environment, application of biochar technology is a new idea.