The invention discloses a voltage-sharing and auxiliary power supply circuit for a photovoltaic inverter and a control method. The voltage-sharing and auxiliary power supply circuit comprises two switch tubes, two clamping diodes, two fly-wheel diodes, two output diodes, two clamping capacitors, a voltage-multiplying capacitor, two output capacitors and two coupling inductors with two windings. According to the voltage-sharing and auxiliary power supply circuit, the voltage gain of a converter and the reduction of the voltage stress of power switch tubes and the diodes are realized through the coupling inductors; the zero-current switch-on of the switch tubes, and the suppression on the back recovery current of the diodes are realized by leakage inductance of the coupling inductors; a clamping circuit formed by the clamping diodes and the clamping capacitors effectively absorbs voltage spike when a main switch tube is switched off, and realizes loss-less transfer of energy; due to the voltage-multiplying capacitor, the gain of the converter is further improved, and the voltage stress of the power switch tubes and the output diodes is further lowered; and in addition, the circuit is convenient to control, and the input current ripple is low, so that the voltage-sharing and auxiliary power supply circuit is suitable for photovoltaic grid-connection power generation conversion occasions having relatively high power, high gain and high efficiency.