Aiming at the problem of work in process backlog and long delivery period in A production line of M enterprise, this paper analyzes the reason by the situation value stream mapping and puts forward choosing the appropriate level of automation under the condition that the improvement benefit is greater than the input cost, to overcome the constraints like material supply is not timely and technological property. To improve and draw the future value stream mapping and create a continuous flow of production line through the technological process, layout, frock and other aspects of improvement. After creating continuous flow in the production line, the production cycle shortened by 13 days, transport distance reduced by 41 meters, workshop area savings of 168 square meters, the number of operators decreased by 6 people, laid a solid foundation for enterprise transformation and upgrading.