Considering the engineering geology,hydrogeology and environmental conditions in the site of Sciences & Education Building deep foundation pit project of Wuhan No.2 Hospital,the single-pipe high-pressure jet grouting method was adopted to prevent underwater from flowing into foundation pit.The process was depicted in details.The practice proves that this method successfully stopped the flow of upper stagnant water.During excavation,no seepage occurs,which facilitated the subsequent construction.And it also proves that single-pipe high-pressure jet grouting method is very suitable for water-prevention and reinforcement of foundation pit in urban areas because of its convenience of construction,low cost and no need for excavation.