Abstract: The study of active time limit (duration) of ductile shear bel t can re veal the important restraining condition of geological event. However, there was no matured method to determine the time duration of ductile structural event di rectly. In this paper we will present some preliminary results of a study aimed to solve this problem based on the chemical and physical information of structur al rocks and stress minerals in the ductile shear belt. A specific dating method , i.e. the structural strain-rate method, has been developed and used in our pr oject. The application of this dating method includes following steps: 　　1. to obtain the strain-rate by calculating the paleo-stress; 　　2. to attain the restrained strain by calculating the volume factor; 　　3. to achieve the time duration of geological event on the base of r estrained strain and strain-rate. 　　The structural strain-rate method has been applied to date the Sushong phosphor o us deposits of ductile shear belt type and a duration time of 1±0.1Ma was obt ained for the ductile shear belt.