The invention provides a load reducing structure and an oil pumping unit comprising the same. The load reducing structure comprises a casing pipe and a sealing pipe arranged in the casing pipe, the sealing pipe is internally provided with a load reducing piston, and a ring-shaped cavity is formed between the load reducing piston and the sealing pipe; the sealing pipe is provided with a breathing hole for communicating the ring-shaped cavity and a pipe cavity of the casing pipe; and the load reducing structure further comprises an on-off control valve which is installed at the breathing hole and used for controlling on-off of a flow path between the ring-shaped cavity and the pipe cavity of the casing pipe. The load reducing structure solves the problem that the size of load reducing forceof a load reducing device is affected by the difference between the casing pressure and the oil pressure in the prior art.