The purpose of this study was to investigate how a mobile collaborative augmented reality (AR) system affects learners' knowledge construction behaviors and learning performances. In this study, 20 undergraduate students were recruited and divided into dyads to discuss given questions with the assistance of mobile collaborative AR system named AR Physics. The participants' knowledge regarding elastic collision was evaluated through a pretest and a posttest that occurred right after the treatment. Learners' knowledge construction behaviors were qualitatively identified according to a selected coding scheme and then were analyzed by adopting sequential analysis. The results indicated that learners significantly gained their knowledge on the topic of elastic collision after completing the given task by manipulating AR Physics system. Furthermore, sequential patterns of learners' behaviors during knowledge construction activities were identified.