A machine vision method based on an eigenvalue realization algorithm was proposed to determine the FY-4 satellite structural modes of vibration. An experiment was designed to prove the feasibility of the proposed method. The experiment results show that the first mode 0.32 Hz and the second mode 1.57 Hz of the FY-4 satellite structure were both clearly distinguished from the background by the proposed method. The comparison of the results of the proposed method and that of simulation and gyroscope testing shows that the error rate of the proposed method is below 0.1% for the first mode and below 6% for the second mode, which is feasible for engineering applications.