A method for improving power amplification efficiency of a Doherty power amplifier, wherein the method is applied to the Doherty power amplifier that has two paths of Doherty circuit units (101, 102) connected in parallel, each of the Doherty circuit units (101, 102) comprises a main power amplifier (103, 105) and a peak power amplifier (104, 106), the main power amplifier (103, 105) and the peak power amplifier (104, 106) are connected in parallel, and the method comprises: detecting, by a control circuit, an output power of the Doherty power amplifier when the two main power amplifiers (103, 105) in the Doherty power amplifier operate in a main power amplification state, in which a power amplifier operates in class B or class AB, and the two peak power amplifiers (104, 106) operate in a peak amplification state, in which a power amplifier operates in class C; sending, by the control circuit, a control command to a bias circuit when the control circuit detects that the output power of the Doherty power amplifier is less than a preset value, wherein the control command comprises values of gate voltages required for turning off the peak power amplifiers (104, 106) in the Doherty power amplifier, and values of gate voltages required for keeping one of the main power amplifiers (103, 105) in the main power amplification state and for operating the other one main power amplifier (103, 105) in the peak power amplification state; receiving, by the bias circuit, the control command that is sent by the control circuit; adjusting, by the bias circuit, gate voltages of the main power amplifiers (103, 105) and the peak power amplifiers (104, 106) according to the control command, thereby causing the peak power amplifiers (104, 106) to be in an off state, and the one main power amplifier (103, 105) to be in the main power amplification state and the other main power amplifier (103, 105) to be in the peak power amplification state. detecting, by a control circuit, an output power of the Doherty power amplifier when the two main power amplifiers (103, 105) in the Doherty power amplifier operate in a main power amplification state, in which a power amplifier operates in class B or class AB, and the two peak power amplifiers (104, 106) operate in a peak amplification state, in which a power amplifier operates in class C; sending, by the control circuit, a control command to a bias circuit when the control circuit detects that the output power of the Doherty power amplifier is less than a preset value, wherein the control command comprises values of gate voltages required for turning off the peak power amplifiers (104, 106) in the Doherty power amplifier, and values of gate voltages required for keeping one of the main power amplifiers (103, 105) in the main power amplification state and for operating the other one main power amplifier (103, 105) in the peak power amplification state; receiving, by the bias circuit, the control command that is sent by the control circuit; adjusting, by the bias circuit, gate voltages of the main power amplifiers (103, 105) and the peak power amplifiers (104, 106) according to the control command, thereby causing the peak power amplifiers (104, 106) to be in an off state, and the one main power amplifier (103, 105) to be in the main power amplification state and the other main power amplifier (103, 105) to be in the peak power amplification state.