The invention discloses a public opinion detection platform construction method based on a block chain technology. The public opinion detection platform construction method comprises the steps of: establishing a user public opinion monitoring centre at first, distributing public and private key pairs to personal users, and providing digital signature service, filtering and historical analysis for internet information; establishing a personal user comment publishing infrastructure platform; setting up a block chain foundation platform published to the internet information; establishing an internet information writing mechanism based on a block chain; and, setting up an internet data storage centre based on a cloud storage platform, and storing original data in a remote cloud data centre after encrypting the original data through the public key of a user. The public opinion detection platform construction method disclosed by the invention has very important significance in the aspects as follows: the public opinion detection is standardized; the personality right, the portrait right, the privacy right and the intellectual property of the personal users can not be infringed, etc.