Ministries and commissions of the central government have proposed "functional games" as one of the grips to promote the transformation and upgrading of the game industry, but there is a lack of scientific and systematic guiding theories for the design of functional games. An attempt was made to propose a functional game design framework from a meso perspective of design methodology by combining the methods of textual close reading, case analysis and game criticism between the existing macro narratives and case experiences. Based on the criteria, contents and organizational structure of functional game design in three dimensions:value, professionalism and playability, a "ternary symbiosis" design paradigm was formed. Based on this paradigm, the functional game examples in multiple fields are designed and tested to verify the feasibility and scientific validity of this paradigm in guiding design practice.