Abstract: Six Gansu alpine sheep with an average weight of 28 kg were fitted with permanent rumen fistulas to investigate the nutritional value of fennel (Foeniculum vulgare) straw and shell on sheep in a 3×3 Latin square design. The digestibility of dry matter, nitrogen, organic matter, neutral detergent fiber, acid detergent fiber, calcium, phosphorus of fennel straw and shell were 61.63% and 62.11%, 64.66% and 66.47%, 62.50% and 62.63%, 72.72% and 71.53%, 68.28% and 67.25%, 20.35% and 23.19%, 35.03% and 31.98%, respectively. The nitrogen retention rate and digestive energy were 49.53% and 52.09% (fennel), and 9.51 and 9.86 (shell) MJ/kg respectively. Sheep digestibility of fennel straw and of shell were higher than those of other roughages. When feeding fennel straw to sheep there were significant differences in the molar ratio of acetic acid, propionate, and butyrate, and of pH and the ratio of acetic acid to propionate in rumen fluid (P<0.05). There were no differences in total volatile fatty acids or in molar ratio of other acids and nitrogen in rumen fluid (P>0.05). When feeding fennel shell to sheep, there were significant differences in the molar ratios of acetic acid, butyrate and other acids in rumen fluid (P<0.05). There were no differences in pH, total volatile fatty acids, nitrogen content, the ratio of acetic acid to propionate and molar ratio of propionate in rumen fluid (P>0.05).