The invention provides a three-dimensional wake numerical simulation method based on a 2D_k Jensen model, which can obtain a novel three-dimensional wake model. The method is characterized in that: step 1, calculating an inflow wind shear curve u0 (z) and the turbulence intensity distribution I0 (z) in the vertical direction; 2, calculating that expansion coefficients kx, z of the wake; 3, predicting that wake wind speed based on the original Jensen model to obtain the initial wake wind speed u* (x, z); 4, calculating that expansion radius rx, r of the wake; 5, utilizing that wake expansion radius rx, r obtained in the step 4, based on the cosine-type velocity distribution proposed by the 2D_kJensen model, three-dimensionally modifying the initial wake wind speed u* (x, z) obtained in thestep 3 to obtain the corrected wake wind speed distribution u (x, y, z). The three-dimensional wake model obtained by the invention inherits the advantages of the engineering model, and has good prediction accuracy for the wake velocity deficit in the direction of flow direction, the cross wind direction and the vertical direction, and can effectively reflect the asymmetric characteristics of thevelocity deficit in the vertical direction, and the calculation accuracy is even better than the numerical simulation result based on the CFD method.