Abstract: Traditional imaging limits to the occlusion of the solid medium such as the wall and can not collect the image of the object which is out of sight. Moreover, the speed of light is supposed to be infinite in traditional imaging, so the imaging process is a steady-state light transport and irrelevant to the time of flight of light, which cannot reveal the specific characteristic of object in the light transport. Single-photon imaging is a technology which can detect very weak photon signal and capture the information of distance, intensity and image of objects synchronously. In this paper, a method of transient imaging for hidden object was introduced. In the imaging process, the time of flight of photon was considered as a variable in light transport to realize transient imaging, combining imaging for hidden object with photon counting and using single-photon array detector as a receiver to reconstruct hidden object. Further, this method was demonstrated by simulation. It provides the basic theory and framework for the transient imaging of hidden object using single-photon array detector, which can help to design the imaging system in real world in the future, as well as to achieve a better understanding of the nature of transient imaging for hidden object.