One hydraulic tunnel was built in 1930's and located in southern Taiwan. The earliest lining was composed of various materials, including concrete without reinforced bars, bricks and stones, depending on the location along the tunnel and the position around the cross section in 1959. It was usually made of concrete in crown and bricks and stones in sidewalls in 1972. A preliminary inspection was carried out in 2003 and was repaired in 2004. The second and third inspection was carried out in 2005 and 2006. This paper will discuss the invert abrasion of hydraulic tunnel, and suggest the design of rehabilitation and maintenance for reference.