Recently, various enterprises including large company and small venture business have got into the Internet business market in a hurry. However, there are few enterprises that have performed strategic Internet business projects to establish competitive advantage based on clear principle. Present Internet business does not harmonize well with existing business, and prevents the business development. This paper introduces the concept of SIS (Strategic Information System) into present Internet business, and shows strategic framework for achieving product differentiation in the Internet product sales. Moreover, taking the case of imaginary company that have several alternatives concern to competitive strategy, we apply the AHP methodology in order to evaluate them.