Two-component developing system has an advantage in durability for high speed and heavy-duty use in an electrophotographic laser printer. For achieving high speed and heavy duty printing, the most important factor is toner supply capability from developing rolls to a photo-conductor surface.In this study, the capability with print speed for each method on the two-component developing system employing magnet rolls composed of rotating sleeves with stationary core including a donor rolls system is examined. For the examinations, some assumptions for factors, which affects to the toner supply capability, and toner mass on the photo-conductor are made.As a result, we found typical speed ranges and their characteristics for the toner supply capability in the two-component developing systems. 700 mm/s print speed can be achieved by the examined methods. The print speed exceeding 1500 mm/s can be achieved by a method of two-roll use of the rotating sleeve with stationary core magnet rolls of 50 mm diameters with different rotation direction.