The invention belongs to the technical field of power equipment fault diagnosis, and particularly relates to a method for estimating a time-delay value of discharge electromagnetic waves based on analog signals. According to the invention, electromagnetic wave signals generated by discharging are received by two sensors and recorded as default analog signals; the received analog signals are converted into two sine wave signals through a band-pass filter with the bandwidth being 400-600MHz; enabling the two sine wave signals to pass through a local oscillator (300MHz); then enabling the signals passing through the local oscillator to pass through a low-pass filter with the intermediate frequency being 100MHz; performing quadrature detection on the acquired signals and signals v21(t), and enabling the signals to pass through the low-pass filter again; calculating the phase difference between the acquired signals by using a formula shown in the description, wherein the phase difference is a time-delay value of the original signals. According to the invention, utilization of digital signal recording devices such as an oscilloscope can be avoided, so that the size, the weight and the economic cost of algorithm matching devices are reduced to a great extent.