“Secondary Public Sentiment”is an important window to observe public feeling and public opinion. Based on the focus on “8•12 Tianjin Port Explosion”, this paper explores the causes and evolution path of "Secondary Public Sentiment" from the interaction and game of government, media and public in press conference. The study found that in addition to the harm, size, scale of public crisis, there are also some deeper causes of “Secondary Public Sentiment” such as the cultural form, the public mood, media of the society and so on. The government's improper response to public sentiment is the immediate cause of “Secondary Public Sentiment”, and that information demand, interest demand, value demand of the public are not met is the fundamental cause of “Secondary Public Sentiment”.