In recent years, China's digital economy has developed rapidly. In the fields of creation, production, dissemination and consumption of cultural content, transmedia narration has gradually become an important phenomenon and trend, so it is of great significance to study the internal mechanism and strategy of transmedia narration. Transmedia narration is gradually rising under the impetus of internal and external factors, and its connotation experiences a dynamic evolution process. The research shows that the internal mechanism of transmedia narration mainly involves two aspects: text creation and industrial operation, which correspond to story world construction and IP operation respectively. In terms of strategy and application, text creation should focus on the perfection and expansion of the story world, and constantly innovate on the basis of respecting the original text to provide inexhaustible cultural source power for the derivation of the industrial chain. Industrial operation should keep pace to the development of IP, so as to realize the linkage of commercial brands and the development of user market.