Abstract—This paper reports our progress of developing a 0.33-THz gyrotron which is based on a compact pulse magnet and can generate broadband coherent THz radiation with bandwidth exceeding 10 GHz and peak power about 2 kW. The design and fabrication of the key components are addressed in detail, including strong-field magnet, pre-bunched cavity, broadband Quasi-Optical mode converter, and Brewster window. The terahertz gyrotron with kilowatt level high power, broadband capability, and compact configuration is the key to high-power terahertz research.