This study aimed to investigate the effects of multimedia computer assisted instruction on using money and purchasing skills for two elementary school students with mild autism. The multiple-probe across behavior design was utilized in the study. The teaching experiment lasted for consecutive 11 weeks and it was conducted 3 times a week, as well as 30 minutes per tim Visual analysis and the C statistic were used to analyze the effectiveness. The results were that MCAI could immediately improve and maintain the performance of purchasing skills. The parents were satisfied the MCAI and their children' performance.