Abstract: Through the researches on the solution micro——textues and wearing micro——structures of the quartz fragments of fault gouge from the wedge——shaped fracture system in the neighbourhood of Shanghai by way of SEN, the paper discussed the following problems: 1. the relative age of faulting, the multi——phase activity of faulting and the migration of faultieg; 2. the stress environment and tectonic background, thus revealing the tectonic implications of the solution microtextures and wearing microstructures of the quartz fragments from the wedge shaped fracture system.