Abstract: It is a critical in tobacco production to enhance the growth of tobacco roots. In this study, a specific tobacco root-promoting agent (STRPA) was tested to investigate its effect on root growth of tobacco seedlings. The results indicated that the root-promoting effects were different when the agent was applied in different ways. The root-promoting effects of irrigating cave was better than irrigating root layer or dipping roots. The root-promoting agent could enhance growth of roots and root biomass of tobacco significantly within 45 d after transplanting. Compared with the equal NPK application, treatment with STRPA could shorten the time of seedling development by 28 hours, and increase the total root number and root dry weight by 18.3% and 25%, respectively, and also enhance N, P and K uptake by 28.3%-50.3%. N, P and K utilization efficiency were improved by 2.9%, 2.7% and 4.8%. Besides, it was found that STRPA promoted root growth and absorption of nutrients through increasing the number of 2nd lateral root, which increased by 36.6% when compared with the equal NPK. These results suggested that STRPA application play an important role in enhancing root development and increasing fertilizer uptake efficiency.