Abstract: The traditional structural operational modal test adopts contact measurement and carries out modal parameter identification in the frequency domain, which has the problems of inconvenient measurement and complicated calculation. Aiming at this problem, a new modal test method based on Digital Image Correlation method and Natural Excitation Technology-Ibrahim Time Domain method is proposed. The industrial camera is used to obtain the speckle image of the structure under environmental excitation, and the stationary response signal of the structure is calculated by Digital Image Correlation method. Then, according to the Natural Excitation Technology-Ibrahim Time Domain method, the cross-correlation function is used to replace the impulse response function, and the response matrix is constructed to establish the mathematical model and calculate the modal parameters of the structure. Taking a simply supported beam model as an example, the numerical simulation and experimental test are carried out. The results show that the method can directly identify the modal parameters from the speckle image of the structure, with high recognition accuracy and strong anti-noise ability. The non-contact test is realized, especially suitable for high temperature and high pressure engineering environment. Parameter identification in the time domain avoids complicated frequency domain analysis and simplifies the calculation.