Based on some detailed theoretic analysis about the recording sampling and reconstructing separation requirement for the digital holography of the spherical reference wave, the relationship fulfilling above requirement for the lateral size of the object and CCD, the distance between the object, CCD and the reference wave point source are deduced. In the recorded plane, it is proved that the superposed complex amplitude of the scattering object is equivalent to that of a point source. The theoretic analysis and experimental results show