In order to study the dynamic characteristics of ultra-weak photon emission in cell and its biological significance,soybean callus are radiated by UV-B radiation with 20μW/cm2 for 2 hours.Delayed luminescence of soybean callus induced by light within 4 days after the UV-B radiation is determined.Delayed luminescence integral intensity,the initial photon number,attenuation parameters and the spontaneous luminescence in ultra-weak photon emission of soybean callus are obtained through the establishment of delayed luminescence dynamics equation and mathematical fitting.The biological significance of these dynamic parameters of ultra-weak photon emission is discussed.The results show that delayed luminescence induced by light of soybean callus within 4 days after UV-B radiation to obey the laws of hyperbolic relaxation.Dynamic analysis shows that the changes of the delayed luminescence integral intensity and initial photon number with the time after UV-B treatment are volatility.The intensity of spontaneous luminescence and the content of malondialdehyde(MDA) are increased after the cessation of UV-B radiation.The peaks of them appear nearly two days after UV-B radiation.Using the ratio of delayed luminescence integral intensity and spontaneous luminescence to define the state parameter Q and the order parameter R of cell,it is found that the changes of Q value or R value of soybean callus cells after UV-B radiation reflect the damage of UV-B radiation on soybean callus and cell recovery process.