In order to improve the quality of tobacco-planting soil, the effects of continuous application of different kinds of biochars on the tobacco-planting soil nutrient contents were studied by a 3 a field experiment conducted in Fengtian Town, Xinning County, Shaoyang City, Hunan Province during 2016–2018. The treatments included CK (no biochar added), T1 (tobacco stem-derived biochar), T2 (wasted tobacco leaf-derived biochar), T3 (maize straw-derived biochar). The results showed that continuous application of different biochars significantly increased the contents of soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP) and available potassium (AK), but had no significant influence on the contents of total phosphorus (TP), total potassium (TK), and alkali-hydrolyzed nitrogen (AN). In the harvest period of 2018, three biochar treatments increased SOM by 10.26%, 9.12% and 6.96%, respectively; increased TN by 10.36%, 18.29% and 9.03%, respectively; increased AP by 6.96%, 18.57% and 9.82%, respectively; and increased AK 16.53%, 33.84% and 13.05%, respectively. With the extension of the test period, the addition of tobacco stem biochar increased SOM most, followed by wasted tobacco leaf biochar and maize straw biochar. However, the wasted tobacco leaf biochar increased TN, AP and AK most. In conclusion, continuous application of biochar can improve soil nutrient contents and soil fertility, and the tobacco leaf biochar has the best potential and prospect of application.