In this paper, we report the calculation of single line-image and double line-image for various configuration of diffractive optical element (DOE), which were designed as one- dimensional plane configuration of bar-shaped pure-phase from the principle of the optical equal-path compensation. The calculated light intensity distributions are in agreement with which from the ideal diffraction disk. There are some weaker noise-light peaks between the double line-image. It should be improved for high precision imaging.