BACKGROUND: Sectional image of the peripheral nerves is a prerequisite for studying the morphological parameters of fascicular groups. Ultra-high precision MicroCT scan can explicitly display the internal morphology of physiological tissues. This study aimed to quantitatively measure the basic morphological parameters of fascicular groups of a peripheral nerve on MicroCT images, obtain the statistical principles and investigate the variation pattern of these morphological parameters during the process of fascicular group extension. METHODS: Peripheral nerve specimens were processed with fat removal, decellularization, freezing, and drying, etc. The morphological parameters including area, perimeter, and the degree of circularity of each fascicular group in the peripheral nerve on MicroCT images were obtained by the image processing method. The cross-sectional area, cross-sectional perimeter, and cross-sectional degree of circularity of the single fascicular group were analyzed. Correlation between the cross-sectional area of single fascicular group and fascicular group extension, the correlation between the perimeter of cross-sectional single fascicular group and fascicular group extension, and correlation between the cross-sectional degree of circularity of single fascicular group and fascicular group extension were analyzed. RESULTS: The cross-sectional area of fascicular groups confirmed the Beta distribution with a dominant proportion of small-area fascicular groups and a low percentage of large-area fascicular groups. Within the range of 3 mm, no significant correlation was observed between the cross-sectional area and the spatial extension of fascicular groups. The perimeter of the fascicular group section was normally distributed. The perimeter of the fascicular group section that did not remain stable immediately after the fascicular group - was split or merged, but it gradually became stable after the fascicular groups extended to a certain distance. The cross-sectional area of the fascicular groups did not change significantly during this period. The degree of circularity of the fascicular group section followed the t distribution pattern with scale/position parameters. Similarly, it gradually approached the average value only after the fascicular groups extended to a certain length. CONCLUSION: Current study revealed the general rules of the basic morphometric parameters of fascicular groups in the process of spatial extension, which provided a pivotal basis for the repair of peripheral nerves and the diagnosis and treatment of neurological diseases and was of academic value and significance.