The present disclosure provides a terahertz detector. The terahertz detector includes a planar array structure that is constituted by a plurality of pixel units, the plurality of pixel units each include N sub pixels and each of the sub pixels includes no more than one signal trigger configured to transform a terahertz signal to an electrical current pulsing signal, and each of the plurality of pixel units detects a signal that is a sum of the electrical current pulsing signals of the N sub pixels, where N is an integer greater than 1.