The research achievements of spectral imaging technology in early detection of botanical diseases were briefly summarized. The plant disease is an important factor that restricts the steady development of agriculture. It is fundamental to botanical production and management to utilize real-time, sensitive, stable detection and prevention methods. Combined multi-spectral images, hyperspectral images, infrared thermal images with plant pathology as well as chemometrics, infected plants can be detected in early stage by spectral imaging technology. It is very meaningful to build a quantitative model that can reflect botanical diseases and its extent precisely.