Near infrared spectroscopy (NIRs) technology and Mie theory are utilized for scattering characteristics research on radiofrequency ablation of biological tissue. Firstly, NIRs is utilized to monitor the radiofrequency ablation surgery rats in real-time so as to explore the relationship between reduced scattering coefficient (RSC) μ′s and the degree of thermally induced tissue coagulation. Then, Mie theory is utilized to analyze the morphological changes of biological tissue so as to explore the basic mechanism of the changes of optical parameters caused by thermally induced tissue coagulation. Results show that there is a close relationship between μ′s and the degree of thermally induced tissue coagulation; the degree of thermal coagulation can be obtained by the value of μ′s; when biological tissue thermally coagulates, the average equivalent scattering particle radius decreases, the particle density increases, and the anisotropy factor decreases.