Abstract: Agronomic measures can be adapted to increase plant K content, which is one of important strategies to improve the quality and output value of flue-cured tobacco. Experiments on K release and field crop response of slowly-released K fertilizers, i.e., PV Coated potassium nitrate, Humic matter coated potassium chloride, and PV and humic coated potassium chloride, were conducted to investigate the K release characteristics and their effects on yield and output value of tobacco. The results showed that the accumulative solubility rates of K of three slowly-released K fertilizers in 28 days under standard conditions were 67.2%, 100% and 87.5%, respectively, of which the performance of PV coated potassium nitrate was the best. The content of soil available K increased at late growth stage of plant treated with the slowly released fertilizers. Compared with the control (common K fertilizer), application of slowly-released potassium increased leaf K content by 13%-39%, yield by 7%-32%, and production value by 7%-32%. In conclusion, the slowly-released potassium fertilizers tested have positive effects on increasing K content and output value of tobacco, and has high potential in tobacco production.