Objective To evaluate the curative effect of immediate nerve suture and delayed nerve suture more comprehensively and more impersonally. Methods 64 guinea pigs were randomly assigned to one of the eight groups and the normal group: groups of immediate FFA, delayed FFA for 7 days, delayed FFA for 14 days, delayed FFA for 21 days, delayed FFA for one month, delayed FFA for 60 days, and delayed FFA for 3 months by turns. Results Two months after nerve suture, figured out the passing rate of myelinated fibers growing from the proximal stump to the distal stump. Observed the form of regenerated fibers under an electron microscope. Calculated the cavity area and the thickness of the regenerated myelin sheath with a computer image processing system. From the study, we can see that the passing rate of myelinated fibers of the group of immediate FFA and the group of delayed FFA for 7 days are significantly higher than that of other groups of delayed suture (P<0.05), whereas the passing rate of the groups of delayed suture for 2 months and 3 months are apparently lower than that of the group of immediate FFA and other groups of delayed FFA. Under the electron microscope, the figure of regenerated fibers of the group of immediate FFA and the group of delayed FFA for 7 days is very similar with that of the normal myelinated fibers: the fibers are relatively thick, the cross sections of the fibers were ellipse shaped, and the myelin sheaths are thick. With the computer image processing system, we see that in the group of the delayed FFA for 7 days, the cavity area of the regenerated myelin sheaths is larger than that of the group of immediate FFA and other groups of delayed FFA. In the case of thickness of regenerated myelin sheaths, the group of immediate FFA and the group of delayed FFA for 7 days took the superiority to other groups of delayed FFA, and these two groups showed no difference with the normal group. Conclution From all kinds of criteria taken from the regenerated myelinated fibers, the curative effect of the group of delayed FFA for 7 days is as good as that of the immediately sutured group. The curative effect is poor if repair the facial nerve 2~3 months after the trauma.