The purpose of this research was to construct a computer-assisted learning system for poor decoders in elementary school to improve their Chinese character decoding accuracy and automaticity. This computer-assisted learning system had the characteristic of computer games in order to increase students’ motivation for practice. Forty-six second-grade poor decoders were selected from an elementary school in Taipei County for learning effects evaluation. There were 24 students in an experimental group and 22 students in a control group. A quasi-experimental design was adopted. The results showed that the decoding accuracy and latency of the experimental group in post-test were both significantly better than those of the control group. These results supported that the computer-assisted learning system designed by this study could help poor decoders to improve their Chinese character decoding accuracy and automaticity.