A novel method is presented for designing the diffractive optical element with large diffraction angle based on the Rayleigh-Sommerfeld Integral. In the design, the target intensity distribution is firstly modified with coordinate transformation and intensity adjustment. Thereafter the modified Gerchberg-Saxton algorithm is adopted to optimize the phase distribution of the diffractive optical element. Our method and the original method, which adopts Frauhofer diffraction integral to calculate the diffraction, are used to design the diffractive optical element to reconstruct a structured light and a square pattern with different diffraction angle. And the result shows that the original method can work well only the diffraction angle below 25°. When the diffraction angle gets larger the reconstructed light field shows significant pillow distortion and uneven intensity distribution. In contrast, our method can achieve the exact diffraction angle and even intensity distribution at all the angle.