Objective To study the difference of reticular fiber of liver of Wistar rat at different ages. Methods Gray scale, area ratio, volume density (Vv) of reticular fiber of portal area, central vein and perisinusoidal space of liver of Wistar rat were observed by using Gomori silver colouring method and image analysis technique. The animals according to the age were divided into 4 groups: 3 months, 13 months, 25 months and 33 months.Results 1.The difference of gray scale of reticular fiber in portal area between group 1,2 and 4 was significant ( P<0.01, P <0.05)respectively. 2. The difference of area ratio of reticular fiber in perisinusoidal space between group 2,4,3 and 1 was significant ( P<0.01, P<0.01, P <0.05)respectively. 3.The difference of Vv of reticular fiber in perisinusoidal space between group 2,3,4 and 1 was significant respectively( P <0.01). 4.In each group the difference of the percentage of Vv of reticular fiber in portal area or central vein or perisinusoidal space between group 2,3,4 and 1 was very significant respectively( P <0.001). 5. In group 1 the percentage of Vv of reticular fiber in perisinusoidal space was the maximal, and central vein the minimal. 6. But in group 2 or 3 or 4 the percentage of Vv in portal area was the maximal, while central vein the minimal.Conclusion Compared with group 3 months, the reticular fiber of perisinusoidal space in groups 13 months, 25 months and 33 months was decreased. The argyrophilia of reticular fiber of portal area in 33 months was reduced.