Abstract: By means of the sedimentary characteristics analysis for two sides of the basin syndepositional faults in Yilan Mining Area, it determined four main syndepositional faults. These faults presented on NE orientation strike, formed a stepped reverse normal faults combination, and their movements mainly took place during the time when Dalianhe formation were formed, with a grow index between 1.3 to 2.2. Their activity characteristics were closely related to the basin margin faults. Both of them played an important role in the control of the sedimentary environment evolution.