A drum pedal assembly includes a frame, multiple bearings, an axle, a drum hammer, a base plate, an extender, a pedal and a transmission element. The frame includes two parallel upright supportive racks and a base. An end of the base plate is pivoted vertically with respect to the base, and the base plate also has a sliding groove disposed along its lengthy direction. The sliding groove has an open end away from the base. The extender is plate-shaped and is slidably inserted in the sliding groove. The pedal has a first end and a second end. The first end pivots to a distal end of the extender by a pivot means. The transmission element is disposed between the second end of the pedal and the axle. The axle and the drum hammer are driven to rotate by the transmission element to rotate as the second end of the pedal pivots.