The diffractive optical elements have the advantages of miniaturization, lightweight and so on. Based on the phase function of transitional axicon, the phase functions of three kinds of diffractive optical elements such as diffractive axicon, helical axicon and axicon array are designed. By using the theory of angular spectrum diffraction, a light field analysis model for diffractive optical elements irradiated by parallel light is established. The light field distribution characteristics of three kinds of diffractive optical elements under monochromatic Gaussian beam illumination are numerically analyzed. The simulation results show that, the diffractive axicon has the same beam propagation performance compared with the transitional axicon, which can generate diffraction-free Bessel beam in the focal depth. The order of the Bessel beam generated by helical axicon is the same as the number of topological charges. Axicon array can generates an array of diffraction-free Bessel beam. The proposed diffractive optical elements can be used in the fields of laser processing and imaging.