An adaptive electrothermal system and an electrothermal apparel are provided. The adaptive electrothermal system comprises a controller, a step-down regulator, a power controller and a load. An input of the controller is configured to receive an input voltage, a first output of the controller is configured to output an input voltage higher than an operating voltage of the load to the step-down regulator, a second output of the controller is configured to output an input voltage lower than or equal to the operating voltage of the load to the power controller, the step-down regulator steps the received input voltage down to a voltage equal to the operating voltage of the load and outputs the stepped-down voltage to the power controller, and the power controller outputs the input voltage it receives to the corresponding load according to a load control signal from the controller. The present invention can receive several input voltages at the same time and provide operating voltages for a plurality of loads at the same time, and has good flexibility and high reliability.