Since Chinese character possess complicated structure, a great mount of handwriting experience is essential to learning Chinese characters. However, young learners often lack motivation for writing Chinese characters, and are hard to maintain their writing interest. In order to help them overcome their learning difficulties, a game-based Chinese character learning system, called CharacterMonster, is developed based on three design principles: Animal companions, open learner models, and learning stages. The purpose of this study is to investigate the effects of game-based system on young learners’ learning achievement, motivation, and interest. The study used a quasi-experimental between-group design, where 48 third graders participated in the experiment. Participants in the control group (n = 23) used a learning system and those in the experiment group (n = 25) used a game-based learning system. The results indicated that: (1) Young learners in both groups gained increased learning achievement but no signifi cant difference was found. (2) Young learners in the experimental group had more increased motivation in the “attention” than those in the control group. (3) Young learners in the experimental group had higher interest in the “extension” than those in the control group.