提出一种非定值相移量的单步相移同轴数字全息算法。对CCD面上的干涉光强进行了分析,用图像相减法算出CCD面上不能确定相位正负的物光波,再记录一帧有相移的干涉光强,来确定相位的正负。其特点是有相移的这一帧干涉光强没有参与物光场大小的运算,只是用于相位符号的判断。该算法对相移误差不敏感。This paper describes an algorithm of numerical reconstruction for coaxial digital holography by means of a single phase-shift. In this algorithm, the intensity of the reference wave, the intensity of the object wave and their interference intensity are recorded, respectively, and the object wave is calculated from these three intensity frames, but the object phase is ambiguous. Then a phase-shift frame corrects the object phase. Compared with the other single phase-shift algorithm, the phase-shift frame in this algorithm is not joins in the calculations of the object wave, but makes it without ambiguity. So, the algorithm is not sensitive to the phase-shifted error.