The launch shaft of Qianwan subsea shielddriven tunnel in Shenzhen is sunk by means of open caisson method. The sinking of the shaft penetrates through grounds with huge volume of high pressure water, as well as muddy layers, silty clay layers, layers consisting of mediumcompact coarse gravels, residual soils and so on. With 18m diameter and 28.54m depth, the shaft is one of the largescale shafts sunk by means of open caisson method. The article presents the sinking construction technology of the shaft in detail.