Holography is an important non-destructive testing method for its unique idea of recording the complete wave field, i.e. both the amplitude and the phase of the light wave scattered by the object. In digital holography (DH), hologram is recorded digitally by CCD and then numerically reconstructed in the computer. The biggest limitation for digital holography is the constraint of the resolution of the CCD camera and the recording distance is very important for DH. This article presents the principles of recording and reconstruction in digital holography. The experimental results and conclusion are also provided in this paper.