The invention discloses a broad-tuning waveguide terahertz radiation source. The broad-tuning waveguide terahertz radiation source comprises a laser pump source, a dual-wavelength parametric oscillator, a cylindrical lens and a panel waveguide, wherein the laser pump source outputs 532nm Q-switched pulses to the dual-wavelength parametric oscillator, the dual-wavelength parametric oscillator generates dual-wavelength pulses which are within the range, wherein the center of the range is a degeneracy point, and the radius of the range is 1064nm, the dual-wavelength pulses are focused through the cylindrical lens, and are coupled to a core layer of the panel waveguide, narrow-linewidth THz waves are generated through the second-order non-linear difference frequency effect, a THz radiation mode is generated through the Cherenkov phase matching mode, and sidewise coupling output is achieved. Due to the fact that the structure is adopted, the tuning range is expanded, broadband tuning within the range from 0.1THz to 7THz can be achieved, high-efficiency coupling of the THz waves is achieved, coherent THz radiation output with broad tuning and the narrow linewidth is finally achieved, and the broad-tuning waveguide terahertz radiation source can be widely applied to the fields such as the biomedicine imaging field, the high-resolution spectral analysis field, the material detection field and the medical diagnosis field.