Abstract: Abstract: Terahertz (THz) radiation is an electromagnetic radiation whose frequency lies between the microwave and infrared regions of the spectrum. THz remains the least explored region mainly due to the technical difficulties involved in making efficient and compact THz sources and detectors. The lack of suitable technologies leads to the THz band being called the "THz gap". Until 1980s, the advent of the femtosecond laser started the advancement in THz generation and detection technologies. THz equipment was then developed by researchers in different labs and commercialized by companies, such as TeraView Ltd. (Cambridge, UK), and Picometrix LLC. (Ann Arbor, MI, USA). With the superior THz equipment, researchers from different disciplines were able to study THz and explored its potential applications in different areas. THz has unique properties in detecting weak intermolecular interaction, and is sensitive to the properties of target objects on both amplitude and phase. THz spectroscopy and imaging techniques are the focuses of current research in this area. Terahertz time-domain spectroscopy (THz-TDS) has been used to evaluate the spectral properties of an object in terahertz range and is being applied in many areas, such as security, semiconductor manufacturing process, communication, and biomedicine. The coherent detection scheme together with the resulting time-domain signal of the terahertz pulse lead to the high sensitivity and excellent contrast that can be achieved in terahertz imaging, which makes terahertz imaging attractive for industrial applications, like metal contacts of a packaged integrated circuit chip, tree-ring analysis, polymer composites and flames, etc. Recently, terahertz techniques have been gradually applied to many fields, including security imaging detection, aerospace, and explosives molecular detection. Experts in field of agricultural research have also actively participated in the application of terahertz technology and have made great progresses. In current paper, the generation and detection methods, sample-making methods, data acquisition and analysis methods of THz spectroscopy and imaging were first systematically summarized and presented. Since there are many factors in agriculture area may influence the THz data acquisition, such as air moisture, samples' thickness, diameter of samples' powder, crop's vulnerability and so on, experimental parameters' determination methods and some testing cases were introduced and demonstrated, which provided a reference for other THz research groups. Afterwards, the research and applications progress of terahertz spectroscopy and imaging technology in agricultural area were carefully reviewed, including agricultural bio-molecular material detection, quality and safety detection of agricultural products, physiology inspection of crops and pollutions detection in agricultural environment, which revealed its great potential and application prospects of terahertz technology in agriculture. The presented explorative studies in agricultural area showed that THz is a promising technology and will definitely play a critical role in many active research areas of agriculture, such as food quality control, crop inspection, and pollutions detection in agricultural environment. However, there are still some problems deserve more attentions in future, such as, what is the 'killer application' of THz in agriculture, how to make the equipment smaller, cheaper, and portable for on-the-spot measurements, etc. which indicated the research directions of THz technology.