This experiment conducted to identify a periodic change of ultrastructures of secondary follicle characteristics during a whole year, reveal the molecule regulation of growth of cashmere. A total of 10 cashmere goats of 1-year old were studied. The paraffin section and ultrathin slices of skin were made each month in a whole year, observed, photographed, and analyzed under light microscope and transmission electron microscope after stained. Following the development of down fiber, the ultrastructures of secondary follicle of Hexi cashmere goat showed a periodic change within a year. There were five different periods during a down fiber cycle. It was observed that the stage of telogen, proanagen, anagen, procatagen, and catagen was in January and February, March and April, May to August, September and October, and November and December, respectively. The key change observed in secondary follicle under transmission electron microscope was inner root sheath. This study illustrated the five different stage of secondary follicle of Hexi Cashmere goat within a whole growth cycle, and has provided more detailed information about the research field of Hexi cashmere goat. Choosing the suitable time to harvest the cashmere may get the profit maximization. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.