Offshore anchor pile is very common in offshore structures such as jacket platform, offshore wind turbine platform and single point mooring system, etc. The installation of anchor pile has significant effect on the cost and process for the whole engineering, in which the lifting is the most important procedure in the offshore operation because it has a great demand for the crane capacity of the vessel. When the anchor pile is too long for the crane to lift vertically, underwater horizontal upending is required in the operation. We elaborate the scheme of underwater horizontal upending for the large-diameter and ultra-long anchor pile offshore lifting and discuss the key technical difficult points. An engineering example of anchor pile installation of single point mooring system in South China Sea is given, through which the reliability of underwater horizontal upending scheme is introduced and validated. This program provides new ideas and approaches for large-diameter and ultra-long anchor pile offshore installation.