Embodiments of the invention provide a power supply apparatus of a tracking system, an inverter and a power supply method. The power supply apparatus is used in a photovoltaic system. The photovoltaic system comprises a photovoltaic module, the inverter and the tracking system. The power supply apparatus comprises a first switch group and a second switch group, wherein the first switch group is serially connected to a first branch; the second switch group is serially connected to a second branch; the first end of the first branch is connected with the output end of the inverter; the second end of the first branch is connected with the first power input end of the tracking system; the first end of the second branch is connected with a power grid; and the second end of the second branch is connected with the first power input end or the second power input end of the tracking system. According to the embodiments of the power supply apparatus, the inverter and the power supply method, dual redundant power supply of the tracking system is realized; and when the power grid does not have power, the inverter supplies the power to the tracking system by controlling the first switch group, so that the power supply reliability of the tracking system is improved.