In the digital media environment, the public opinion management model is undergoing a deep reconstruction. To explore the operational mechanism of public opinion management under the background of media governance, this study analyzes three core issues: information filtering, co-governance logic, and risk control. By sorting out the technology driven information filtering logic, it reveals how data flow and algorithm architecture reshape the public opinion dissemination path. Meanwhile, combined with the collaborative logic of pluralistic governance, the functional evolution of the government, platform, and public in the public opinion governance system is analyzed. The dynamic balance logic based on risk control explores how public opinion governance can dynamically adjust between information transparency and social trust to enhance the accuracy and adaptability of public opinion regulation. Through the comprehensive application of technological optimization, collaborative governance, and risk warning, the media governance system can build a precise information filtering, efficient subject collaboration, and orderly risk control public opinion governance model in the digital media environment.