Abstract: Intake tunnels in Wudongde hydropower station have small turning radius and large section.For lining construction of the top horizontal section of intake tunnel,the structural contour requirements of the lining and the turnover use of steel form jumbo are key problems.And it is difficult to control the lap quality of construction joints on concrete flow surface.On the basis of preliminary research and practice,the lining construction technology for top horizontal section of intake tunnel with small turning radius and large section is formed.By adopting this construction technology,high-quality lap joint between bottom arch and side top arch is achieved by adding turning-over form at the bottom of the steel form jumbo,and the repair investment in the later period is avoided.By adding flexible lap form at the joint of new and old concrete,the problem of smooth connection of transverse joints of concrete flow surface has been solved.Different types of expansion joints are added between steel form jumbos of multi-section assembly type in order that the maximum size deviation of lining of curved section with different radiuses is less than 2cm.As a result,the design requirements and turnover use of steel form jumbo are achieved,and the construction of top horizontal section is compatible with the concrete construction of the straight-line section and curved section.The application results show that the construction technology can meet the concrete quality requirements for the inside section of intake tunnel,speed up the construction progress,and reduce the construction cost.