A beamless mechanic-reversing long stroke pumping unit is provided for petroleum production in diverse types of oil fields. Its mechanic-reversing system consists of differentials, brakes, etc. With two differentials assembled together, taper gears inside them perform revolution and rotation, enabling the pumping unit to achieve direction change and speed change mechanically. The stroke length of the pumping unit can reach 8 meters or longer, and the adjustment process is more convenient than most, by merely tuning the position of the proximity switches. Abrasion of the chains typically caused due to resetting of a motor frequently during operation, is eliminated in this pumping unit. The pumping unit has more reliable operation performance, more convenient maintenance, lower costs, better energy saving effects, and can be applied in land oil fields, offshore oil fields, oil wells with low permeability, etc.