Abstract: An adjustment structure of a rotary sprinkler, including a rotary seat, a plastic rotary tube body, a rubber pad, several adjustment ball valves and a plastic pressing cover. The rotary seat includes a head portion and a tail portion connected therewith. An adjustment member is disposed on the head portion and formed with a fitting hole and a water-incoming head. The tail portion is formed with a fitting hole. The plastic rotary tube body has a close end and an open end. The rotary tube body is formed with an axial channel and several water-outgoing holes are formed on a bottom of the axial channel. The rubber pad is disposed with several concaves. An orifice is disposed on a bottom of each concave. Each adjustment ball valve has a lower ball portion and an upper post portion. An upward tapered sprinkling hole extends from a center of a top face of the post portion to a bottom end of the ball portion. The plastic pressing cover is formed with several through holes on a surface.