Braking accidents of drum brakes which fixed in synchronizing shaft is one of the most serious accidents of hydro-floating ship lift (HFSL).Depend on design parameters of Jinghong HFSL project,the paper analyzes the security risks of ship lift in working condition of the accident,proposes counter-measures and control index.Furthermore,theoretical calculation method of risk prediction is put forward.Through prototype observation tests,the validity and reliability of theoretical calculation method and counter-measures are verified.