A terahertz parametric radiation source based on Stimulated Polariton Scattering (SPS) is an optically coherent terahertz source, characterized by high coherence, frequency tunability, and operation at room temperature. The basic principle of terahertz parametric radiation based on SPS, commonly used nonlinear crystals, and coupling techniques are firstly introduced. Then typical techniques and research achievements in recent years, both domestical and international, are summarized regarding gain enhancement and output performance improvement. Additionally, the progress in the application of terahertz radiation sources in material concentration detection is reviewed. Finally, the key technical issues and development trends of terahertz parametric radiation sources are analyzed.