Abstract: Provided are a device and a method for measuring pore size distribution of porous media through a harmonic analysis. The device includes a signal application system, instruments for measuring pressure and displacement, a signal processing instrument and a sample and fluid storage container. According to the disclosure, an oscillating flow is applied to a sample through the signal application system, pressure and displacement signals are collected by the signal processing instrument, a harmonic analysis is performed on the signals, and a frequency response of admittances of the porous media is calculated according to harmonic analysis results of the signals, so that the pore size distribution is obtained.