How do people trust government at different levels amid the Covid-19 pandemic as well as infodemic? How do media of different political nature shape public trust in government during the pandemic? What role does expert system, exemplified by professional institutions and groups, play between media exposure and government trust?These findings accentuate the critical role played by expert systems in the modern society’s trust ecology. Firstly, while trust in expert systems based on knowledge authority and trust in government based on political authority are all forms of public trust in abstract system in modern society, the former will significantly influence the latter. Secondly, although both professional groups and institutions are important parts of the expert system, people’s trust in abstract system is better embodied in its living agents. Thirdly, in addition to direct contact with expert systems, people are more dependent upon the gateway of media to form their experience of and thus their trust in expert systems.In major public health crisis, government needs to pay attention to both state media and non-state media. On the one hand, government should enhance the defining and guiding role of state media to strengthen the mainstream public opinion during the infodemic. The state, on the other hand, must reinforce its regulation of non-state media, with a special attention to misinformation and malicious speech related to medical institutions and practitioners. Moreover, policy makers need to take full advantage of expert systems in the process of crisis management, including crisis evaluation, decision making, information release and social mobilization, to achieve social integration and better governance.A national survey found (1) Public trust in central government is higher than local government during the pandemic, confirming a hierarchical order of government trust in China. (2) The more the public is exposed to Covid-19 information through state media, the higher their trust in both central and local governments, whereas non-state media exposure has no impact on government trust. (3) State media exposure influences government trust through public trust in both medical institutions and scientists, yet non-state media exposure affects government trust only through public trust in health providers, which means state media exposure can change government trust by more forms of expert trust, leading to a greater impact than non-state media exposure. (4) While public trust in scientists serves as a stronger mediator than trust in medical institutions between state media exposure and government trust, only trust in medical institutions shows a negative mediation effect between non-state media exposure and government trust.