Quantitative three-dimensional imaging of cells of Chinese medical decoction pieces can provide a new method for microscopic identification of decoction pieces. To improve the digital holographic image quality, the recording and reconstruction processes of image-plane digital micro-hologram recorded with spherical reference light are studied theoretically and experimentally. A method for measuring the recording parameters of the holographic imaging system such as the magnification, object distance by using a standard test target is proposed. The two popular phase-unwrapping methods are compared experimentally. The results show that the image-plane digital micro-holography recorded with spherical reference light is characterized by more information recorded, very easy reconstruction and the real-time observation of the investigated specimen for determining the region correctly. The parameters of the holographic system can be determined accurately by using the reconstructed intensity image of a US Air Force test target. The unwrapped phase with big depth sample can be obtained accurately by using the lateral-shearing-based least square (LSBLS) algorithm. Using the edge reorganization technique the cell image can be better displayed.