It was proposed during the 20th National Congress of the Communist Party of China that it was necessary to improve the public opinion supervision system and improve the public opinion guidance mechanism for major public opinions and emergencies. This paper focuses on public crisis events. In consideration of the characteristics of viral spread, emotional spread, and mixed spread of online public opinion in public crisis events, and the government's governance of public crisis events, where time pressure is extremely high, uncertainty risks are great, and risk causes are complex, it is of great importance to build an accurate identification system for public opinion risks on social media network in public crisis events. This paper carried out theme crawlers on multiple mainstream social platforms. According to the number of information releases and event node combinations, public crisis events were divided into five stages, namely the public opinion embryonic period, the public opinion expansion period, the public opinion hot discussion period, the public opinion fluctuation period and the public opinion fading period, and public opinion data were collected and organized; This paper carried out custom named entity recognition and emotion annotation to expand the public opinion corpus of public crisis events; it also built a fused BERT pre-training language model based on the Transformer framework based on classic cases of sudden public crises, conducted public opinion emotion recognition and emotion analysis, and explored emotional characteristics of online public opinion in the five stages of perception. In addition, this paper explored the correlation of various potential risks of online public opinion from the perspective of public opinion emotions so as to improve the identification system of online public opinion risks.