The invention discloses a new-type terahertz broadband waveguide detector structure, comprising waveguide input impedance match sections, a substrate circuit in a cavity of a waveguide, a grounding diode and an output low-pass filter. A whole detector circuit is greatly simplified and the length of a substrate is greatly reduced. According to the structure, detection is finished by the diode in the waveguide cavity, the detector circuit is greatly simplified, the length of the circuit substrate is reduced, the broadband performance of a detector is improved, and the simulation difficulty is reduced. According to the structure, the change of an electric field mode results in the increase of the isolation degree of an input/output end for radio frequency signals, and a TM11 mode also can be suppressed by reducing the width of an input waveguide, thereby reducing reflected signals. Moreover, a shielding microstrip line cavity in which a rear end low-bass filter is located has relatively high suppression effect on the radio frequency signals. According to the high suppression effect, influences of structures such as the filters on a front end waveguide match structure can be greatly reduced.