First, the machine source positioning method, that is, through the cell phone mobile data transmission method to determine the location information. This is different from the GPS we often hear, is through the cell phone base station, cell phone signal transceiver, will be automatically connected to the nearest signal transmission tower, all the activities of the cell phone, can contain base station information signaling data signaling tower screening back, so that you can track the location of the cell phone user and the path. This is the most commonly used method and the most efficient big data screening tool for this new outbreak. Second, analysis through social interaction information, such as nearby neighborhoods and market personnel contact contacts. This does not mean judging by social software information, but combining the existing data, through telephone surveys, mapping visits and other ways. Beijing after the outbreak of the "knock on the door action", this time Beijing nearly 100,000 community (village) workers into 7120 communities (villages), checking more than 300,000 people. Thirdly, it can be confirmed through the item information, Beijing outbreak at first, after analyzing the diagnosis of people, identified the Xinfadi market as the origin, and then further identified seafood market, found that the salmon plate carrying the virus, through the identification of items related to close contacts to rapid screening, which is also an important means of screening.