In recent years, the smartphone owner growth grows rapidly. The development of mobile technology chages users ’ experience in communication, bringing a more personal, instant, and interactive communication model. Skype, one of the most popular web-based communication software, also provides the APP version for the mobile phone users. However, Skype for mobile phone , equipped with a smaller multi-touch interface that totally differs from the traditional computer interface, raises a lot of usability problems. This study applied usability testing and evaluation method to examine the Skype interface for mobile phone, and provides some suggestions. (1) The contacts ’ information should be more consistent; (2) the icons of instant message should be clearly distinguished; (3) the search function should be more efficient; (4) group classification and the icons of screen ’s size of video calling should be added. Finally, this study used Axure RP to design a prototype, hoping to cater to users ’ need and expectation.