The utility model relates to a developing device in an electrophotographic imaging device. The developing device comprises a box body, a protecting cover, a stirring device, a powder feeding roll, a developing roll and a powder discharging knife, wherein the box body is provided with a developing agent cabin; the stirring device is supported between the opposite lateral walls of the box body and is positioned in the developing agent cabin; the powder feeding roll is supported between the opposite lateral walls of the box body and is positioned at the outlet of the developing agent cabin; the developing roll is supported between the opposite lateral walls of the box body; the powder discharging knife is supported at the two sides of the box body for controlling the developing agent and consists of a metal board and a metal elastic trip. As the technical scheme is adopted by the developing device and the mode that the developing agent is charged to limit the powder output is changed, the technical problems of abnormal noise, overlarge driving force, bad printed product and the like caused by the elasticity and the installation position of a metal pressure spring existing in the prior art are solved, thereby ensuring the quality of various produced developing agent boxes to be the same basically, simplifying the process control and avoiding the complicated technique problems that the working surface of a metal block is oxygenized, sprayed and the like; in addition, the cost of the material is lowered obviously.