A diamond compound cutting head comprises a cutting head body. A diamond compound blade is welded to the front end of the cutting head body, the cutting head body is slantly installed on a drill bit drill body, and the diamond compound blade is slantly welded to the front end of the cutting head body. The front knife face of the diamond compound blade is a plane. The front knife face of the diamond compound blade is approximately parallel to the axis of the drill bit drill body. Cutting stress of the diamond compound blade is approximately parallel to the axis of the cutting head body. By changing the installing angle of the cutting head body and the welding angle of the diamond compound blade, the angle of the cutting front knife face is changed so as to reduce the included angle between the front knife face of the diamond compound blade and the axis of the cutting head body. After the angle is changed, the area of the front knife face is reduced, the area of a poly crystal diamond layer is reduced, and the cost is reduced; the included angle between the axis of a mounting hole and the cutting speed direction is increased, and cutting stress F in the cutting process points to one end of the hemispherical cutting head body and is favorable for enabling the diamond compound cutting head to be tightly fixed in a mounting blind hole.