In the twenty-first century, there are still many difficulties arise on software development. For example, the growing commercial demand variability, but the software maintainable level over time becoming less and less. We have to raise the importance of software design. Using good software design approachs to face the increasingly complex commercial demand. Therefore, this study analyzed the large-scale enterprise systems for the software design problems. Based on the theory of software design, software design methodology, software architecture, design pattern and design principle, this study introduce three software design approachs:"Flexible Integration Design", "Loosely Coupled Design", and "Parameter Table Design". Using the extensibility, flexibility, pluggability and reuseability to design system integration solutions: "Unified Accounting Rule Table" and "Unified Interface". This will help the large-scale enterprise systems for software development to increase quality and efficiency.