A systematic study is made on the construction technology for the deep weathered slots of subsea tunnels on basis of the construction practice. Construction technologies, including the advance geology forecasting of deep weathered slots, watersealing grouting, watersealing effect examination, determination of advance reinforcement schemes, determination of excavation methods, monitoring and measurement and emergency countermeasures for water/mud gushing, are carefully studied and effective construction schemes and construction methods are summarized in the paper, which can provide reference for similar projects in the future.