The invention provides a media data trading method and a system based on a block chain, and a computer storage medium. The method comprises: a data provider device on the block chain processes the source media data into a media data report by utilizing a micro service program provided by a micro service provider device under the condition that the source media data does not come out of the data provider device; the data provider device uploads the first list of media data reports to the media big data trading platform. The data purchaser equipment on the block chain queries the first list based on the key information; if the data purchasing device queries the target report information in the first list, the data purchasing device sends a first transaction request to the media big data trading platform. The media big data trading platform forwards the first trading request to the data provider equipment; the data provider device transmits the media data report corresponding to the target report information to the data purchaser device according to the first transaction request. The safety of media big data transaction is guaranteed and the circulation of media big data is promoted.