The quality of laser beam shaping is improved using binary optics element (BOE) in two ways：design algorithm and phase fitting method. In polar coordinates system, high quality flat-top beam is obtained by using profile-smoothing and Gerchberg-Saxton (GS) hybrid algorithm. In order to get annular output beam, an improved profile-smoothing algorithm is presented. These two algorithms can maintain high energy conversion efficiency without loss in uniformity. Besides, we research how the radius of BOE, sampling number and initial radius influence the phase fitting accuracy. The machinable BOE phase is obtained in Zemax. The evaluation index shows that the phase structure meets the design requirements.