Due to the fact that mobile devices and educational software developed and expanded substantially in recent years, the importance of mobile-assisted learning may be raised. This study aimed to investigate the lack of the experimental design mobile-assisted leaning studies, and tried to make suggestions. Researchers collected all of the experimental studies on mobile-assisted learning published in ERIC and ISI from 2003 to 2013, which amounted to 216 studies. The four primary variables (research design, methods for initial equivalence in quasi-experiment, measuring tools and their reliability and validity, and sample size) were coded and preliminarily analyzed into frequency tables. Results of the study are as follows: (1) Researchers of 33.33% studies conducted the research by pre-experimental design or quasi-experimental design without equating, which were not rigorous sufficiently; (2) reliability and validity of outcome measures were not reported in 80% studies; and (3) sample sizes of approximate 30% studies were inadequate to draw an accurate statistical conclusion.