The present invention discloses a public opinion monitoring method and system of probability topic calculation and matching. The method comprises: data collection and analysis: collecting the page HTML from the data source by using the crawler cluster, using the crawler cluster to analyze the page HTML according to the rule base so as to obtain a plurality pieces of media data, using crawler cluster through an asynchronous mode to store the analyzed documents into a full text retrieval system, and using the crawler cluster through a synchronization method to carry out topic matching on the analyzed documents; Chinese word segmentation: reading documents in the full text retrieval system, combining the topic and content of each document, carrying out segmentation on the combined content, and removing the stop words after segmentation; topic estimate: estimating a topic library and a historical document topic set for the content after segmentation; and topic matching: carrying out inference on documents pushed in real time by the data collection to obtain an actual document topic set, and matching the actual document topic set with public opinion monitoring keywords input by a user to obtain an orderly document set, so that public opinion monitoring is realized.