A control method for improving conversion efficiency of a multi-channel Maximum Power Point Tracking (MPPT) inverter, comprising following steps: in step S1: collecting an input voltage v PVm of a photovoltaic panel in each channel, an input current i PVm of the photovoltaic panel in each channel and a direct-current bus voltage v bus, obtaining an input power P PVm of the photovoltaic panel in each channel, and using input voltages of at least two channels to obtain a voltage difference Δ v PV, wherein m=1, 2,..., M, M is a number of input channels of the photovoltaic inverter MPPT; in step S2: comparing the voltage difference Δ v PV with a preset on-off control judging threshold to obtain a start and stop state of a boost circuit in each channel, a voltage reference signal v PVm ∗ in each channel and a direct-current bus voltage reference signal v bus ∗, wherein the boost start and stop state is determined as follows, in step S21, when |Δ v PV ≥ V THb, turning off a boost circuit in a channel corresponding to a maximum input voltage v PV_max, activating the boost circuits in remaining channels, wherein V THb is a boost on-off control judging threshold 1, and maximizing the input power P PVm by an MPPT module in each channel to obtain the voltage reference signal v PVm ∗ in each channel, the direct-current bus voltage reference signal v bus ∗ using a maximum voltage reference signal v PV _ max ∗; in step S22, when V THb ≥ |Δ v PV | ≥ V THs, activating all boost circuits, wherein V THs is a boost on-off control judging threshold 2, wherein V THs < V THb; and maximizing the input power P PVm by the MPPT module in each channel to obtain the voltage reference signal v PVm ∗ in each channel, the direct-current bus voltage reference signal v bus ∗ using the maximum voltage reference signal v PV _ max ∗; and in step S23, when V THs ≥ |Δ v PV |≥ 0,when the step is performed for a first time, obtaining a voltage V VLMPP at a virtual local maximum power point (VLMPP), turning off all the boost circuits, maximizing a total input power P PV_sum of the inverter by an MPPT module based on the direct-current bus voltage v bus to obtain the direct-current bus voltage reference signal v bus ∗, monitoring a voltage difference between the direct-current bus voltage v bus and the voltage at the virtual local maximum power point V VLMPP, and activating all the boost circuits when the voltage difference between the direct-current bus voltage v bus and the voltage at the virtual local maximum power point V VLMPP exceeds the boost on-off control judging threshold 1 V THb. in step S1: collecting an input voltage v PVm of a photovoltaic panel in each channel, an input current i PVm of the photovoltaic panel in each channel and a direct-current bus voltage v bus, obtaining an input power P PVm of the photovoltaic panel in each channel, and using input voltages of at least two channels to obtain a voltage difference Δ v PV, wherein m=1, 2,..., M, M is a number of input channels of the photovoltaic inverter MPPT; in step S2: comparing the voltage difference Δ v PV with a preset on-off control judging threshold to obtain a start and stop state of a boost circuit in each channel, a voltage reference signal v PVm ∗ in each channel and a direct-current bus voltage reference signal v bus ∗, wherein the boost start and stop state is determined as follows, in step S21, when |Δ v PV ≥ V THb, turning off a boost circuit in a channel corresponding to a maximum input voltage v PV_max, activating the boost circuits in remaining channels, wherein V THb is a boost on-off control judging threshold 1, and maximizing the input power P PVm by an MPPT module in each channel to obtain the voltage reference signal v PVm ∗ in each channel, the direct-current bus voltage reference signal v bus ∗ using a maximum voltage reference signal v PV _ max ∗; in step S22, when V THb ≥ |Δ v PV | ≥ V THs, activating all boost circuits, wherein V THs is a boost on-off control judging threshold 2, wherein V THs < V THb; and maximizing the input power P PVm by the MPPT module in each channel to obtain the voltage reference signal v PVm ∗ in each channel, the direct-current bus voltage reference signal v bus ∗ using the maximum voltage reference signal v PV _ max ∗; and in step S23, when V THs ≥ |Δ v PV |≥ 0,when the step is performed for a first time, obtaining a voltage V VLMPP at a virtual local maximum power point (VLMPP), turning off all the boost circuits, maximizing a total input power P PV_sum of the inverter by an MPPT module based on the direct-current bus voltage v bus to obtain the direct-current bus voltage reference signal v bus ∗, monitoring a voltage difference between the direct-current bus voltage v bus and the voltage at the virtual local maximum power point V VLMPP, and activating all the boost circuits when the voltage difference between the direct-current bus voltage v bus and the voltage at the virtual local maximum power point V VLMPP exceeds the boost on-off control judging threshold 1 V THb.