Abstract: Aiming at the intra-group and inter-group externalities between the service consumers and providers that the two-sided platform links, and focusing on the optimal pricing policies of platform with the service providers having strong intra-group externalities, the impact on user participation and profit structure are studied. The research shows that the optimal pricing policies of the platform for consumers and service providers include charging fees, being free of fees and giving subsidies, which can make the total profit of the platform positive, that the internal externalities have a profit-loss impact on the profit of the two-sided platform, and that the size relationship between the intra-group externalities and the quantitative relationship between all externalities together determine the contribution of the service supply and demand sides to the platform profit.

Key words: two-sided market, inter-network externality, intra-group externality, pricing policies