The invention discloses an electric door closer of a fireproof door. The electric door closer comprises a sliding rail, a support arm, a sliding block, a first bracket, an electromagnetic valve, a release link, a blocking plate and a shaft block, wherein a caulking groove is formed in one side, close to the blocking plate, of the release link; one end of the release link is hinged at a position close to a bottom wall of the first bracket; an action end of the electromagnetic valve is connected with the other end of the release link; one end of the blocking plate can be embedded in the caulking groove of the release link; a first compression spring is mounted between the end of the blocking plate and the bottom wall of the first bracket; a compression rod for driving the shaft block to be embedded in an arc-shaped groove of the sliding block is mounted on the other end of the blocking plate; after the electromagnetic valve is electrified, a core pulling end of the electromagnetic valve retracts to drive the release link to overturn; after separating from the caulking groove, the blocking plate overturns anticlockwise, the shaft block moves towards a bottom wall of the sliding rail and slips off the arc-shaped groove; the sliding block slides along a slideway on the sliding rail. When the electric door closer is in a normal state, the electromagnetic valve is not electrified; when the electric door closer works, the electromagnetic valve is electrified, the use cost of the electric door closer is reduced; through dual control of the electromagnetic valve and a temperature sensing glass ball, the safety of the electric door closer is improved.