This pilot study first introduced the language characteristics of children with autism. The application of Picture Exchange Communication System (PECS) was then introduced both in theory and in practice by using a 7-year-old autistic subject to examine the effects of PECS on this subject. The subject was taught 40-minute each lesson, three times a week and the teaching lessons lasted for one month. The results indicated that subject could learn PECS from stage 1 to stage 4 and could generalize what he learned to his daily life.