Abstract: Experimental postmortem ultrastructural changes of the liver cell in mice in moisty temperature at 20℃ with method of freeze-fracture were observed by scanning electron microscopy (SEM). The results showed slightly extended endoplasmic reticulum and enlarged mitochondria in mice liver cellls 3 hour after death. The neucli of liver cell did not change until 6 to 1.2 hours after death. The ultrastructural changes of liver cell were found to correlate with the post-mortem intervals. And the results also indicated that it could be used as morphological indicator to determine the time of death. The advantages and disadvantages of freeze-fracture method and resolution of SEM for obser. vation of ultrastructure were disccussed as well.