A computer-aided assessment method of man-machine interface(MMI) for display and control centers(DCC) in the power plants was proposed. The digital Chinese human body model(HBM) for assessment was developed based on UG/OPEN API; the design-related ergonomics standards of DCC were studied, and the quantitive objective indexes are used as the assessment indexes; the quantifying methods of assessment indexes were also studied and determined. Finally, the computer-aided assessment software system was developed based on UG/OPEN, with using UG/Open API, MenuScript and UIStyler development tools. The Chinese HBM, assessment indexes, and quantifying methods all were integrated into this software system. It combined the mentioned assessment methods with the digital design platform of UG and it achieved the real-time interaction between design and assessment of DCC.