With the increasing demand for spatial resolution performance of astronomical observation, it is urgent to develop telescopes with optical synthetic aperture of 10 meters, 100 meters or even kilometers. Traditional optical synthetic aperture imaging technology faces the challenge of high precision phase technology, it is difficult to extend the long baseline SAR imaging to optical band. The measurement method of intensity interference is relatively insensitive to phase, which provides a possible technical scheme for optical synthetic aperture with long baseline. The development history and key scientific problems of the stellar intensity interferometer and the speckle interferometer are reviewed respectively, and the technical characteristics and development potential of the space intensity autocorrelation synthetic aperture telescope are analyzed. By summarizing the characteristics of the three techniques, it can provide reference for the development of long baseline optical synthetic aperture imaging system.