Abstract:Karst phenomena are widely distributed in the South China and usually exist in the hidden form. It is hard to find out its exact positions and sizes in advance by the existing exploration means, which has caused the great harm to the engineering foundation. Therefore, the improper treatment will seriously threat the safety during the construction engineering of karst area. Combined with the construction practices of pile foundation bottom in karst area, the treatment technique and construction technology of the karst cave at the bottom of pile foundation after the finished pile are introduced, which has a certain engineering reference for the pile foundation engineering in karst area.