Abstract: The surge motion significantly influences the thrust coefficient and wake development characteristics of floating offshore wind turbines (FOWT). Considering the surge motion and changes of the thrust coefficient over time, a dynamic wake model under surge is proposed to predict the dynamic wake response and thrust coefficient various. A high-order Gaussian function describes the wake profile. The model is developed through three steps. Firstly, the hub position change during the surge motion is corrected. Secondly, the relative inflow velocity at the rotor is modified by considering the additional velocity induced by the surge. Finally, a dynamic model of the thrust coefficient is established based on the first-order sinusoidal motion of FOWT. Comparisons with wind tunnel test data show that the model predicts the wake with a root mean square error of 4.04% during upwind surge and 1.47% during downwind surge. The modified thrust coefficient agrees well with CFD simulation results. Under high-frequency surge conditions (f ≥ 0.072 Hz), the average relative error between the two is within 1%. Finally, an analysis of the wake distribution characteristics at different time points reveals that, under surge motion, the wake deficit at a fixed downstream location of the FOWT fluctuates periodically around its time-averaged value. The wind speed at the wake center is significantly influenced by the surge frequency. Under high-frequency motion (f = 0.09 Hz), the fluctuation amplitude of the wake center wind speed reaches 7.8%. The model proposed in this study can be employed to predict the wake of floating wind turbines and provides a foundational basis for the development of layout optimization models for floating offshore wind farms.