A power adjustment method, which is applied in a human body security check device or an inspection device provided with a millimeter wave transceiver, wherein an adjustable power attenuator (203, 3013) is provided in a millimeter wave signal transmitting link of the millimeter wave transceiver, and wherein the method comprises: controlling the adjustable power attenuator (203, 3013) to adjust its power attenuation value to be consistent with the target power attenuation value; characterized in that the method also comprises: obtaining a current humidity value by detecting the ambient humidity around the millimeter wave transceiver using a preset humidity sensor (201, 3011); determining a target power attenuation value of the adjustable power attenuator (203, 3013) according to the current humidity value, the sum of the target power attenuation value and a power attenuation value caused to a millimeter wave signal by the ambient humidity being a constant value; wherein the step of determining the target power attenuation value of the adjustable power attenuator (203, 3013) according to the current humidity value comprises: determining the power attenuation value caused to the millimeter wave signal by the ambient humidity according to P pad 1 = ax + b, and determining the target power attenuation value of the adjustable power attenuator (203, 3013) according to P pad 1 + P pad 2 = C, wherein x refers to the current humidity value, P pad 2 refers to the target power attenuation value, C refers to a total power attenuation value, and both a and b are constants. controlling the adjustable power attenuator (203, 3013) to adjust its power attenuation value to be consistent with the target power attenuation value; characterized in that the method also comprises: obtaining a current humidity value by detecting the ambient humidity around the millimeter wave transceiver using a preset humidity sensor (201, 3011); determining a target power attenuation value of the adjustable power attenuator (203, 3013) according to the current humidity value, the sum of the target power attenuation value and a power attenuation value caused to a millimeter wave signal by the ambient humidity being a constant value; wherein the step of determining the target power attenuation value of the adjustable power attenuator (203, 3013) according to the current humidity value comprises: determining the power attenuation value caused to the millimeter wave signal by the ambient humidity according to P pad 1 = ax + b, and determining the target power attenuation value of the adjustable power attenuator (203, 3013) according to P pad 1 + P pad 2 = C, wherein x refers to the current humidity value, P pad 2 refers to the target power attenuation value, C refers to a total power attenuation value, and both a and b are constants. obtaining a current humidity value by detecting the ambient humidity around the millimeter wave transceiver using a preset humidity sensor (201, 3011); determining a target power attenuation value of the adjustable power attenuator (203, 3013) according to the current humidity value, the sum of the target power attenuation value and a power attenuation value caused to a millimeter wave signal by the ambient humidity being a constant value; wherein the step of determining the target power attenuation value of the adjustable power attenuator (203, 3013) according to the current humidity value comprises: determining the power attenuation value caused to the millimeter wave signal by the ambient humidity according to P pad 1 = ax + b, and determining the target power attenuation value of the adjustable power attenuator (203, 3013) according to P pad 1 + P pad 2 = C, wherein x refers to the current humidity value, P pad 2 refers to the target power attenuation value, C refers to a total power attenuation value, and both a and b are constants.