The invention relates to a magnetic field generator insert cartridge for applying a magnetic field in the molding process of polymer materials. The insert cartridge aims to solve the problem that the temperature of the heatable insert cartridge of the prior magnetic field generator can not be accurately controlled in heating process, so the requirements of the hot press molding and the cross linking (vulcanization, curing) reaction of polymer materials on the temperatures can not be met when a magnetic field is applied. The insert cartridge comprises a first insert cartridge, a second insert cartridge, a third insert cartridge, a first heat insulation layer, a heating plate, an asbestos layer, a thermal couple and a temperature controller, wherein the heating plate consists of a mica plate, a resistance wire and two insulating boards; the resistance wire spirally winds around the mica plate; the mica plate is clamped and fixed by the two insulating boards; the thermal couple is inserted in a round hole in the side wall of the third insert cartridge; the cold end of the thermal couple inputs a temperature signal to the temperature controller; and the output of the temperature controller regulates and controls the voltage of the resistance wire. The insert cartridge is used as a magnetic field generator insert cartridge.