Social media plays a role in the development of a personal knowledge system and personal creativity. This paper develops a theoretical model to analyze the relation between social media and creative expression in design education. Based on the flow theory, the generativity theory, and TAM, the paper collects data regarding the usability dimension of students in social media, and their creativity, and examines the proposed model through statistical software SAS9.4 to analyze the data. A correlation is seen between the usability dimension of social media and the creative expression dimension, with an especially significant positive connection between perceived ease of use and perceived usefulness, as well as capturing and challenging. The adoption intention of social media is positively correlated with creative expression, while the usability dimension of social media has positive correlation with broadenings and negative correlation with surroundings; however, neither is significant. This reveals that aimlessly accumulating knowledge through social media will not help students improve their creativity; instead, overusing social media hinders one from understanding the real world and gaining inspiration. The paper is conducive to better social media design and higher personal creativity.