A row-control-free corncob picking header device of a corn harvester comprises a supporting frame, a hydraulic motor, a reel, a lifting cylinder, a corncob picking header, a hydraulic pipe, a passageway, stem pulling rollers and corncob picking plates, wherein the supporting frame is installed on the upper portion of the corncob picking header, the rear end of the supporting frame is hinged to the corncob picking header, and the hydraulic motor is installed at the front end of the supporting frame; the lower portion of the hydraulic motor is connected with the reel, the front end of the lifting cylinder is connected to the middle of the supporting frame, the rear end of the lifting cylinder is connected to the corncob picking header, the passageway is placed under the reel, the corncob picking plates are arranged on the two sides of the passageway respectively, the stem pulling rollers are correspondingly arranged below the corncob picking plates on the two sides of the passageway, and the hydraulic pipe connected with the hydraulic motor is arranged on the front portion of the supporting frame. According to the row-control-free corncob picking header device of the corn harvester, the distance between adjacent guide-feeding devices can be adjusted freely so that the whole device can be compact in structure. When the device is used, the device is installed on the rear portion of the corncob picking header of the corn harvester, corns with any row distance can be smoothly guided into a corncob picking single-row, and the row-controlled harvesting mode required by a corncob picking header in the prior art is changed in the true sense.