The utility model discloses a driven wheel adjusting device of a belt-type conveyor, which comprises an adjusting slide groove, a lead screw positioning sleeve, a pull rod sleeve, an adjusting lead screw and a bolt group, wherein a driven wheel is fixed on the adjusting slide groove; the adjusting slide groove is fixed on a frame beam of the conveyor through a bolt; one end of the pull rod sleeve is in sliding connection with a main shaft of the driven wheel, and the other end of the pull rod sleeve is installed inside the lead screw positioning sleeve; one end of the adjusting lead screw is screwed into the pull rod sleeve, and the other end of the adjusting lead screw is installed inside the lead screw positioning sleeve; and the lead screw positioning sleeve is installed on the frame beam of the conveyor through a bolt. The driven wheel adjusting device which is formed by assembling the adjusting slide groove, the lead screw positioning sleeve, the pull rod sleeve, the adjusting lead screw and the bolt group, and the device is arranged inside a protective sleeve structure, so that the device can be prevented from being rusty rapidly in different environments that the belt-type conveyor is frequently used and particularly under the field severe environmental condition, the driven wheel of the conveyor can be conveniently adjusted at any time, the appearance is attractive, and the structure is compact.