The invention discloses an automatic constant-temperature electronic cigarette and a control method thereof. The electronic cigarette comprises an electronic cigarette body, a heating assembly, a controller and a power source are arranged in the electronic cigarette body, the power source supplies power to the heating assembly and the controller, the controller comprises a resistance value detection module, a comparison module and a heating time adjusting module, the resistance value detection module comprises a resistance value change amplitude detection unit, the input end of the resistance value change amplitude detection unit is electrically connected with the heating assembly, the comparison module comprises a resistance value amplitude comparison unit, the input end of the resistance value amplitude comparison unit is electrically connected with the output end of the resistance value change amplitude detection unit, the heating time adjusting module comprises a prolonged heating adjusting unit, a standard heating adjusting unit and a shortened heating adjusting unit, and one of the prolonged heating adjusting unit, the standard heating adjusting unit and the shortened heating adjusting unit is communicated with the heating assembly. The automatic constant-temperature electronic cigarette has the advantages of being capable of automatically adjusting smoke temperature, smoke amount and smoke smoking taste uniformity, saving energy and preventing dry burning.