Abstract: Low-level jet is a common specific wind condition in the atmospheric boundary layer. The maximum shear height appears in 100 m~350 m according to the observed data. With the development of wind turbines, the hub height has entered the influence range of the maximum shear wind speed of low-level jet. It is necessary to re-examine the influence degree of low-level jet on the dynamic response of large wind turbines under operation state, and discuss the possible harm to the operation safety of wind turbines. The mainstream 15 MW wind turbine is taken as the research object. On the basis of validating the validity of the wind turbine dynamics model and of the low-level jet wind field model, the dynamic response of the offshore floating wind turbine and the onshore fixed wind turbine under normal operation state is compared by taking the jet height and jet intensity as control variables. The extreme value analysis of aerodynamic load and displacement response of wind turbine are carried out upon the peak factor method, and the extreme value prediction formula of blade tip displacement response based on jet intensity is proposed. The study results show that the influence of low-level jet on the aerodynamic load and on the displacement response of wind turbines cannot be ignored even if different turbines are in normal operation state, and that the maximum difference of the influence degree of the low-level jet on the offshore floating wind turbine and on the onshore fixed wind turbine can reach 20.94%. A mechanism explanation based on the low-level jet effect is provided for the tower sweeping phenomenon of large wind turbines, and an operation idea is proposed to avoid the tower sweeping due to the influence of low-level jet.