The invention discloses a method for calibrating the absolute delay time. The method comprises the following steps of generating a standard sine wave table by using a data processing platform; using asignal processing module to process the standard sine wave table; obtaining the standard voltage current signals and sending the standard current signals to equipment to be tested; when the preset time delay threshold value is reached, using the data processing platform to process the standard sine wave table; obtaining a sampling value SV message; sending the sampling value SV message to the equipment to be tested; performing analog quantity collection by the equipment to be tested while receiving the sampling value SV; obtaining a first sapling value of the quantity threshold value of a preset collecting point; respectively performing fast Fourier transform on a second sampling value corresponding to the first sampling value and the sampling value SV message; obtaining the phase time difference value of the first sampling value and the second sampling vale, i.e., the absolute delay time; determining the absolute delay time of the equipment to be tested according to the absolute delay time and the preset time delay threshold value.