This article points out that social media has become the main channel for news dissemination，reshaping the trust structure of the audience towards news. The research，analyzing from the dimensions of communication mechanism and contextualization，discovers that institutional authority is the foundation of trust，and the historical trust inertia of the audience towards official sources continues to play a role；algorithm personalization and platform interaction structure，while amplifying trust，may also lead to trust deviation and solidification；the dynamic game among institutional reputation， interaction structure and algorithm logic jointly shapes the news trust generation path in the Chinese social media environment，providing references for related theories and governance practices.