Crank shaft net torque of pumping units is a volatile alternating load,while output torque of a general motor is basically constant.Thus,load characteristics of pumping units and motors are not able to “harmoniously” match each other;this resulted in a higher output of the motor,lower efficiency,and higher energy consumption of the pumping units.A new six-bar linkage pumping unit is presented according to moment-changing theory.It allows to adjust automatically following the changes of polished rod load,and achieves small crank shaft curve fluctuation.The new pumping unit improves motor efficiency,reduces motor output power,and saves energy.According to the design scheme,kinematics and kinetics models of the new six-bar linkages pumping unit are built up.An optimum design on the main performance parameters and functional analysis were performed. Crank shaft net torque of pumping units is a volatile alternating load, while output torque of a general motor is basically constant .hus, load characteristics of pumping units and motors are not able to “harmoniously ” match each other; this resulted in a higher output of the motor, lower efficiency, and higher energy consumption of the pumping units. A new six-bar linkage pumping unit is presented according to moment-changing theory. Let can to adjust automatically following the changes of polished rod load, and achieves small crank shaft curve fluctuation. new pumping unit improves motor efficiency, reduces motor output power, and saves energy. According to the design scheme, kinematics and kinetics models of the new six-bar linkages pumping unit are built up. An optimum design on the main performance parameters and functional analysis were performed.