[Objective] In the context of public health emergencies, it is of great value to the management departments to calculate the netizens' trust in government microblogs and explore the reasons for the change of trust.

[Methods] According to the objects of comment, the topic similarity between the comment and the microblog post, and their sentiment, the trust values of the comments of the government microblogging are calculated. Combined with the trust value of likes and that of forwarding, the comprehensive trust degrees of the netizens to the government microblogging are calculated.

[Results] Using the microblog data of COVID-19 for empirical analysis, it is found that topics related to industrial fighting epidemic can enhance the trust in government microblogging, and the role of the Chinese epidemic situation on the trust in government microblogging is affected by industrial fighting epidemic and government actions. There are great differences in the evolution trend and reasons of the trust in government microblogging in different industries.

[Limitations] Only the events and the microbloggers are considered as the objects of comments.

[Conclusions] The results reveal the changing trend and reasons of netizens' trust in government microblogging of different industries during the COVID-19, and provide data and method support for government departments to make decisions, repair and improve public trust, and guide public opinion during public health emergencies.