Abstract: As the interactive Internet application, weibo has become the important way for the general public to express opinions and emotions. This paper used haze problem in Chai Jing's Below the Dome as the entry point, and collected more than a thousand relevant weibo data. The experiment combined sentiment lexicon with sentiment analysis technology to analyze sentiment of Sina weibo 's text public opinions, and then expressed the public opinion situation of the event quickly, timely and objectively. In addition, through the analysis of the status quo of haze, it can help the relevant functional departments understand public opinions and play a necessary role in decision-making.