Conducted is system analysis on Stage II Engineering Design of Gas Field A in Turkmenistan,applied is the top-level design idea to study the business contract module, project definition module and project organization and construction module in the project. Discussed is the mode used for governmental financing loans and providing EPCC services and introduced are methods used for project start-up and planning, avoiding contract disputes, realizing project overall goals and pursuing the largest economic benefits for every party involved in the project. Top-level design lays a solid foundation for efficient propulsion and risk control of the project and provides harmonious inner and outer circumstance.