Nowadays, with the advent of the mobile phone, we have relished the convenience in many aspects. The emergence of MALL theory contributes to the enhancement of autonomous learning. The traditional way of cramming method can no longer serve students' need anymore. Hence, many students gradually use smart phones as an convenient source of knowledge after class. This empirical study aims to analyze the effectiveness of vocabulary apps on smart phones with scientific data and offer suggestions to the improvement of both vocabulary apps and students.