In this study, to learn the routine of Tantui, a branch of martial arts was taken as an object of research. Fitts' stages of motor learning and augmented reality (AR) were applied to a 3D mobile-assisted learning system for martial arts, which was characterized by free viewing angles. With the new system, learners could rotate the viewing angle of an image freely in a three-dimensional space, zoom in or zoom out the image, and adjust its playback speed. The experimental participants were divided into two groups, i.e., the experimental group (EG) and the control group (CG). The same coach instructed the EG through the 3D mobile-assisted learning system with AR capability while the CG was taught through a 2D video-based learning system on common mobile devices. Finally, a one-way ANOVA was performed to investigate the differences in learning performance between the two groups. Also, questionnaire surveys and interviews were conducted to understand whether the 3D free viewing angle of AR was helpful to cognitive learning of motor skills, learning motivation, learning satisfaction, and conditions of technology acceptance. It is expected that the findings herein will contribute to mobile-assisted learning and martial arts teaching in the future.