A voltage regulator and a voltage regulating method thereof and a voltage generator using the voltage regulator are disclosed by the present invention. The voltage regulator of the present invention uses a first switching unit and a second switching unit to respectively provide an operational transconductance amplifier (OTA) with different closed-loop feedback paths during a first period and a second period. In this way, an auto-zeroing unit is able to exactly store an input offset voltage presented between the inverting input terminal and the non-inverting input terminal of the OTA.