Abstract: A long stroke pumping unit comprising a tower mounted on a base and a counterweight-polished rod system which bestrides a top wheel mounted on the top of said tower, employs an electric motor as its prime mover. The motor rotates in a fixed direction, and through a crank mechanism the rotation of electric motor is turned into a linear reciprocating movement which is in an approximately simple harmonic fashion, and then, by means consisting of fixed pulley blocks and a travelling pulley block assembly the stroke of said reciprocating movement is multiplied and transmitted to the counterweight-polished rod system. The stroke can be easily changed by changing the effective length of the crank, also, it can be selected within a great extent by changing the number of pulleys engaged in operation.