Abstract: An uninterruptible photosensing power controller for streetlight has a control box and a photosensing device. The control box has two sets of power cables and a socket. One set of power cables is connected to a utility pole and the other set of power cables is connected to a streetlight. The socket serves for the photosensing device to be plugged therein and fixed thereon. The photosensing device triggers the control box according to a luminance level of ambient light to control to supply a power from the utility pole to the streetlight. Since the photosensing device is directly fixed on the control box, the present invention simplifies the process and reduces the labor in installing a conventional power controller for streetlight.