To investigate the effects of biochar from different feedstocks on acid soil improvement, nitrogen(N) mineralization and nitrification, acid red soil was selected as experiment material, and different biochar prepared from rice straw, rice husk and wood were added to carry out a 50?day indoor culture experiment. Five treatments had been set: CK (control), F ( chemical fertilizer), B₁ (rice straw biochar with chemical fertilizer), B₂ (rice husk biochar with chemical fertilizer), B₃ (wood biochar with chemical fertilizer). The soil basic physic?chemical properties, enzyme activity and the contents of ammonium N and nitrate N were determined to analyze the relationship between soil properties and N transformation. The results showed that rice straw biochar improved soil pH better than wood biochar and rice husk biochar. Compared with CK and F treatment, the soil pH in B₁ treatment increased by 0.10 and 0.64 units, respectively. Besides, the contents of soil organic matter, total N, available phosphorus and available potassium in B₁ treatment were also significantly higher than that of other treatments. Furthermore, the application of fertilizer (F) and biochar (B₁, B₂, B₃) significantly increased the soil N mineralization rate and nitrification rate, and there were significant differences in different biochar treatments. Throughout the 50?day experiment,compared to F treatment,the average N mineralization rates in B₁, B₂ and B₃ treatments decreased by 81.5%, 87.6% and 28.1%, respectively. Meanwhile, treatment B₁ and B₃ could hold soil nitrate N and increase the nitrification rate by 12.0% and 16.0%, respectively, while B₂ treatment reduced the nitrification rate by 18.5%. In addition, the soil carbon and N cycle?related enzymes activity in different biochar treatments were significantly different. Totally, the results indicated that biochar from different feedstocks have different effects on the physic?chemical properties of acid red soil, and the differences of soil properties could affect the N transformation, and rational application of biochar can hold soil N and reduce N loss.