Abstract: Based on the brief understandings of the development of System Methodology(SM) and Decision Paradigm (DP), a review of the intrinsic relations between SM and DP is given out. Then, the paper discusses the guidance and illumination functions of new system methodologies e.g. Integrated System Methodology (ISM) to develop a new DP called CP, which is mainly faced to Complex System (CS) problems.

Key words: System Methodology(SM), Decision Paradigm (DP), Complex System (CS), Complex Paradigm (CP)