This paper reports a holographic interference method for measuring wavefront of laser beam. A telescopy is placed in an arm of ring interferometer, so an expanded laser beam and a reduced laser beam are produced. These two beams should interfere and form a co-axial hologram. The curvature radius of the laser beam is obtained by measuring localization of the reconstructed image. The measurement precision of the wavefront curvature radius corresponds to the depth of focus, three time higher than common interferometer. And the pattern is direct visual and spatial resolvable.