For constructing the cast-in-place batter pile on batholith under the offshore construction conditions of without cover and isolated pier，several technology difficulties exist，such as mud counterfort and bottom sediment reducing pile bearing capacity，soak softening of hole wall lowering the soil strength，hard to ensure quality of long concrete core column，difficult to drill hole on batholith and long hole forming period. In terms of these construction difficulties，we carry out research on reducing the depth of pile into rock and improving the bearing capacity of pile foundation. We apply the post-grouting measure after the cast-in-place pile construction，compact sinking slag and batholith fissure，and test the post-grouting pile foundation. The results show that the post-grouting measure increases pile bearing capacity，reduces the depth of pile into rock，guarantees concrete core quality and decreases the construction period.