The purpose of this study is to explore the relationship of playfulness factors of electronic games and the participation and sustainability of e-learning. This research adopted focus group interviews to identify the playfulness factors, and in-depth interviews to inquire the application of these factors into e-learning design. The major findings are as follows: (1) the definition of six playfulness factor types of electronic game including positive feeling, negative feeling, interpersonal communication, virtual & real communication, and psychology, and others; (2) the effect of playfulness factors applies to e-learning participation and sustainability; (3) the appropriateness of applying playfulness factors into e-learning design: and (4) the design suggestion for the game-style e-learning.