The present disclosure illustrates a voltage regulator having wide common voltage operating range and an operating method thereof. The voltage regulator can solve a problem of the prior art that the excessive low or high common voltage easily causes the voltage regulator to operate abnormally. In addition, the voltage regulator completes the operation of boosting voltage by increasing additional switch transistors and error amplifiers without using a complex design, so that the lower common voltage can still satisfy with the operation condition of the voltage regulator to output the correct output voltage accordingly.
