This study develops a theoretical model with respect to a platform because recently, being progressing global IT industry, interests of various factors, which make this field evolving, are growing gradually. Among these various factors especially as new business model in IT sector, platform is becoming a dominant cause. Its definition however, does not precisely elucidate in stead of that impact on platform market is rising significantly. Furthermore, platform, in which business environment has each different background, is burgeoning a cardinal structure to obtain diversified economy model. In accordance with waxing importance for platform environment, its definition needs to be specifically clear including researches, at which how IT companies can behave to be contingent upon dynamic and technology environment. Therefore, we examine a variety of platform definition based on previous research and illustrate how IT firms cope with method of application for platform classification, business model and strategic options through case studies by Apple, Google, and Amazon. Finally, we analyze the factors to being influenced on global platform business and expound what implications can be helped to IT companies on platform base management.