Abstract: Some problems such as the difficulty in pile pull-out and operation cycle prolonging may occur in the field operation of the jack-up platform. In order to improve the efficiency of pile pull-out, the author conducted the experimental study on the relationship between the pull-out resistance and the waiting time of pile insertion. The experiments were made by taking Marine Oil 941's leg and spudcan as the sample, the undisturbed soil of Bohai Bay in Tianjin as the experimental site. The results show that the of pullout resistance increases with the increase of waiting time, the increment becomes gradually smaller, and eventually tends to be stable. Without regard to the influence of water jetting of high pressure sea water on the upper and lower surface soil of the spudcan before pulling out the pile, the pull-out force is about 2 times of the weight of the leg when the pull-out resistance is stable.