This study utilized the computational thinking educational board game named “Robot City” as the instructional material. The board game corresponds to the concept of sequential, selection, repetition and subprogram of the programming language. This study integrated the augmented reality into helping the seventh grade students cultivate the competence of computational thinking from the board game. The study also explored the effects of student's learning achievement and cognitive load. The participants of this study were 50 students from two classes. They were divided into an experimental group (n = 27) and a control group (n = 23). The students in the experimental group used augmented-reality system to support their learning in the computational thinking board game. The students in the control group used the augmented reality learning system integrated with traditional teacher-centered multimedia instruction to support their learning in the computational thinking board game. From the experiment results, the learning effectiveness of the experimental group was significantly higher than those of the control group. The cognitive load of the students in the experimental group was significantly lower than those of the control group.