The development trend of complex packaging machinery is used the multi- axis synchronous servo drive technology to replace the traditional mechanical transmission technology. For the packaging process execution end high- speed reciprocating motion requirements,a design method of multi bar mechanism by using the electronic cam driven is proposed. The curve planning method of the electronic cam is discussed. The mathematical model of the cam movement is established by the NURBS curve method,and the smooth cam motion curve is obtained. The simulation and experiments show that using the NURBS curve fitting method can meet the requirements of speed,acceleration and multi axis synchronization,so as to ensure the smooth and no impact of the push movement,and improve the output flexibility.