Mobile devices are more powerful and portable nowadays with plenty of useful tools for assisting people handle daily life. With the advance of mobile technology, the issue of mobile learning has been widely investigated in e-learning research. Many researches consider it is important to integrate pedagogical and technical strengths of mobile technology into learning environments. This review study focuses on the investigation of add-on impact of mobile applications in learning strategies. We surveyed recent researches including context awareness, pedagogical strategy-enhanced learning scenarios, as well as collaborative and socially networked mobile learning. Through this review study, essential characteristics of mobile learning were identified and discussed. With the essential characteristics, we emphasized on the add-on impact of mobile learning and elaborated mobile learning model in learning strategies.