The lock’s foundation pit is usually excavated in dry condition formed by dewatering.Based on the analysis of the special foundation Yunyan river lock which consists of soft soil and silty soil,and combining with the actual excavation,we research a new method to avoid the traditional dewatering method.According to the research on the local trial-excavation technology for the chamber soil,we sum up a new construction technology that can directly excavate the chamber’s deep foundation pit,set the inverted filter locally and utilize water channel in the permeable area.