In an engineering-to-order (ETO) company, organization and management of manufacturing process is differ from common products because of the complexity of product. A project-based manufacturing (PM) planning model for product final assembly is proposed based on single-piece and small-batch production model so that the characteristics of complexity, specificity and high complex product manufacturing process can be met by means of projected-based manufacturing. The method of layered network planning under project-based manufacturing can transform the objects of planning from parts to assembly cell in the course of final assembly that has some time-based buffer for planning; simultaneously a resource-task matrix is build for the whole assembly process. The matrix can achieve the relatedness between manufacturing resources and assembly task, and follow the resources loads in order to realize the matching of planning and resource against project product.