The rapid development of the Internet-based sharing economy has met more and more social needs. Based on this background, this research first analyzes the development model, development stage, and advantages and disadvantages of the sharing economy. From the perspective of the platform, this research defines the "incremental market share index" with the "relative comprehensive advantage" indicator as to the starting point and studies the competitive relationship and equilibrium state of sharing platforms and professional platforms entering the market at the same time and platforms as leaders and followers in different situations. Finally, this research analyzes the living space and social value of sharing platforms in the market. The main research results are as follows: 1) If a sharing platform and a professional platform enter the market simultaneously, the sharing platform may exit the market only when the relative comprehensive advantages of the professional platform are sufficiently significant. Otherwise, even in the face of the relative comprehensive advantages of professional platforms, sharing platforms can still survive. There will be a situation where two types of platforms compete. Moreover, the low return requirements of idle resources make it possible for sharing platforms to squeeze professional platforms out of the market. 2) Compared with entering the market competition simultaneously, the shared platform has more obvious advantages as a follower to participate in the competition, and the platform has a late-mover advantage. 3) From the perspective of the social value of sharing platforms, the entry of sharing platforms into the market does not necessarily increase social welfare. Only when the sharing platform reaches the optimal platform output level from the perspective of social welfare, its entry into the market can compensate for the diversified losses of the professional platform and achieve the optimal compensation effect.