The invention relates to a method for automatically demolding a commutator injection-compression mold, comprising the steps of: loading a molding material into a material compartment plate, arranging commutator segment components in a middle mold of a middle template, performing mold closing on a heating plate, the material compartment plate, an upper template, the middle template and a lower template, filling the molding material into the commutator segment components and performing injection-compression molding; and then, separating the heating plate and the upper template from an upper oil cylinder and supporting the separated heating plate and upper template by a suspender, separating the upper template and the lower template and supporting the separated upper template and lower template by a pull rod, jacking the middle template by ejector rods driven by a lower oil cylinder so as to separate the middle template and the lower template, taking out the middle template, and jacking out a semi-finished product of the commutator in the middle template by a delivery foot on an injection-compression demolding frame. A device for automatically demolding the commutator injection-compression mold is characterized in that the heating plate is connected with the upper oil cylinder, the lower template and a base plate are provided the ejector rods in contact with the middle template, and the ejector rods are connected with the lower oil cylinder; the suspender is arranged between the material compartment plate and the heating plate, and the pull rod is arranged between the base plate and the material compartment plate. The method and the device disclosed by the invention has the advantages of realizing automatic operation of demolding, reducing labor intensity and increasing working efficiency; and the specification or quantity of the commutator segment components on the middle template can be increased properly.