The invention discloses a power supply noise model establishing method used for solving the problem of inaccurate acquisition of the power supply noise model in the prior art. The method comprises the following steps: sampling voltage values at the selected voltage testing nodes corresponding to each IC chip on a single plate; converting each acquired voltage value into a frequency domain to acquire a frequency domain voltage sequence composed of each converted frequency domain voltage value; acquiring impedance matrices of the single plate, each selected voltage testing node of which is taken as the testing ports, and multiplying the inverse matrices of the impedance matrices by the frequency domain voltage sequence to acquire the power supply noise model corresponding to each IC chip onthe single plate. The invention further discloses a device for establishing the power supply noise model. Each IC power supply noise model established by adopting the method of the invention can accurately carry out the design of the power supply distribution system, thereby reducing the design cost of the power supply distribution system.