The invention discloses a light lifting beam of a monorail crane for a mine and a monomer for the light lifting beam. The monomer comprises a motor, a hydraulic hoist (comprising a spline shaft, a self-lubricating bearing I, a self-lubricating bearing II, a chain wheel and the like), a frame, a load bearing wheel component, a chain, a chain case, a lifting appliance and other parts, wherein the motor is fixed on the frame through a bolt and provides torque for the chain wheel through the spline shaft so as to drive the chain to lift the lifting appliance; and a butterfly buckle is used for connecting the frame with the chain. When an object with high tonnage is carried, two light beam monomers are combined with each other, are connected with each other through a pull rod and are fixed with each other through a pin shaft. According to specific conditions of carried materials, pull rods with different lengths can be used. When materials with low tonnage are carried, a single light beam monomer can be used. The lifting and lowering of the lifting appliance are controlled by a ball valve. Lifting appliances in different forms can be used, so that the light lifting beam and the monomer are convenient to replace and have high adaptability.