The industrial internet and the sharing economy are changing the way companies allocate resources and plan capacity. The mode of sharing idle capacity among manufacturing companies has gradually shown a broad development space and economic benefits. This paper studies the platform's optimal pricing strategy under the two decision goals of profit maximization and social welfare maximization in the context of platform-based capacity sharing. Research shows that the equilibrium profit of the platform under the registration fee model is greater than the equilibrium profit under the fixed transaction fee model. The platform profits of the two pricing models are positively correlated with the network externalities and service sensitivity coefficients of both the supplier and the demander, negatively correlated with the supplier's capacity pricing, and are a concave function of the platform's service level. The pros and cons of the two pricing models’ social welfare and the platform's subsidy strategy for bilateral users are all related to manufacturing costs that are offset by supply-side network externalities. In addition, there is a situation where social welfare and platform profits are better at the same time, which is also the direction for the healthy development of capacity sharing platforms.