A natural heat dissipating layout of an electrical or electronic heating device dissipates heat in a natural cooling way. The layout comprises a heater and one or more main heat source power modules installed on the back surface of a flow channel of the heater. The layout positions of the main heat source power modules on the heater satisfy the following requirements: when the length of the heater along the flow channel direction is X and the width is Y and the number of the main heat source power modules is N, the distance between two geometrical centers of contact surfaces of any two adjacent main heat source power modules and the heater is a = Y / N, and the distance between each main heat source power module on the edge and the edge along the widthwise direction of the heater is b = Y / 2N; and when the number of the main heat source power module is one, the geometrical center of the contact surface of the main heat source power module and the heater coincides with the geometrical center of a base board surface of the heater. The layout solves the problem that unreasonable layout positions of power modules on a heater cause temperature rises.