Abstract：This paper explains the importance of the "User-Centered" Design thoughts in the design of human-machine interface，and describes how to design mobile phone interface with high usability for the elderly user groups by the use of User-Centered Design．The application of User-Centered Design theory in the mobile phone interface design is described in detail from needs analysis，user analysis and interaction design．The final user testing proved that User-Centered Design improved the usability of mobile phone user interface，and solved the difficulty of the popularity of mobile phones in the old-aged user groups．
2010, Vol. 1 