The present invention discloses a power converter with improved line transient, comprising: a power stage circuit including at least one power transistor switch which operates to convert an input voltage to an output voltage; an error amplifier comparing a feedback signal with a reference signal to generate an error signal; an input voltage instant variation extraction circuit extracting an instant variation of the input voltage and generating a signal relating to the instant variation; and a PWM comparator generating a PWM signal according to at least a ramp signal, the error signal, and the signal relating to the instant variation, to thereby control the operation of the power transistor switch in the power stage circuit.