Abstract: During the digital transformation of manufacturing industry, small and medium-sized enterprises （SMEs） suffer from pain points including data silos, non-standardized processes, experience-based decision-making, as well as high costs and poor adaptability of large-scale ERP systems. Centered on core ERP management concepts, this paper develops a lightweight, scalable and data-driven purchase-sales-inventory system by combining the multi-variety and small-batch production characteristics of manufacturing SMEs with technologies such as microservices, containerization and data middle platform. Built on the C/S architecture, the system establishes a unified data foundation to connect the full business chains of procurement, production, warehousing, sales and inspection, realizing automated workflows, data interconnection and intelligent risk early warning. It also incorporates innovative schemes of data visualization, intelligent decision-making and SaaS deployment. Practical applications verify that the system can eliminate data barriers, cut operating costs and boost production and inventory turnover efficiency, offering a feasible technical route and practical reference for SMEs to achieve low-cost digital transformation.