The present invention provides a power-factor converter with nonlinear conversion ratio, wherein the power-factor converter includes a first inductor, a second inductor, a rectifier circuit and a switch circuit. The switch circuit is arranged to be switched to form a circuit equivalent to a parallel connection of the first inductor and the second inductor during an inductor-charging-phase for charging the first inductor and the second inductor in parallel by an AC power source, and form a circuit equivalent to a series connection of the first inductor L1 and the second inductor L2 during an inductor-discharging-phase for discharging the first inductor and the second inductor to the rectifier circuit in series.