The wave relative frequency in the coordinate system moving with current and the angle between the direction ofwave propagation and that of current are computed based on the wave dispersion relation. The current field iscomputed by solving the depth averaged shallow water equations. The wave field is computed by solving the mild-slope equation which has taken the currents effect into account. A numerical model is established using a finiteelement method for simulating the wave shoaling and diffraction in current over a mild-slope, and the numericalresults are reasonable to compare with the experimental data. The wave relative frequency in the coordinate system moving with current and the angle between the direction of wave propagation and that of current are computed based on the wave dispersion relation. The current field is calculated by solving the depth averaged shallow water equations. The wave field is computed by solving the mild-slope equation which has taken the currents effect into account. A numerical model is established using a finite element method for simulating the wave shoaling and diffraction in current over a mild-slope, and numerical values ​​are reasonable to compare with the experimental data.