Raman mapping technique is applied to detect mono-hepatocellular carcinoma. The area of characteristic peak at 786, 1450 and 1658 cm-1, which assigns to DNA, lipid and protein, is calculated. According to normalized values image in the corresponding scan location of the cells, the distribution of Raman characteristic peak of these materials in liver cell is reconstructed. The results show that, the distribution of DNA, lipid and protein is exhibited clearly by this Raman mapping system, and the reliability is validated by fluorescence staining. The micro distribution of material in the cells can be confirmed by the imaging of characteristic peak, which provides reliable evidence for Raman detection and liver cancer diagnosis.