The value searching range of reference light intensity is large in Zhang′ s algorithm. Based on an analysis of the theory of holography, we can take multiple parameters into consideration to further reduce the value searching range for the reference light intensity in two-step phase-shift digital holography and verify its effectiveness experimentally through in-axis transmission and reflection holography. It is shown that the twostep phase shifting holography combined with our proposed methods is effective in eliminating the zero-order image and twin image from hologram without deteriorating the reconstructed image but being benefit for saving computation cost about 20%.