A DC-DC converter and a DC-DC converter operation method are provided. The DC-DC converter includes a power stage, an error amplifier, a pulse width modulation (PWM) generator, and a gate controller. The power stage includes a first transistor and a second transistor. The voltage dividers are configured to perform a voltage division on a first node of the power stage and a second node to generate a first voltage and a second voltage. The first node is an output node of the DC-DC converter and the second node is a node between the first transistor and the second transistor of the DC-DC converter. The comparator is configured to compare the first voltage and the second voltage to generate a turn-on time signal of the first transistor according to a comparison result.