Through a case study, this paper recorded the process of training a 5-year 11-month old girl with multiple disabilities to use the picture exchange communication system (PECS) and the changes of this girl's communication behaviors at each training session. The procedures of each training phase developed by Frost and Bondy (2002) were strictly followed. The training sessions mainly took place in this girl's home and in that of her aunt. After receiving the 4- phase PECS training, the girl not only learned the skill of using PECS but also made persistent progress at each training phase. Additionally, results also showed that the more pictures the girl learned, the less her disruptive behaviors affected her communicative functions.