Abstract: ObjectiveThis study investigated the effects of vitamin C on Northwest Tibet Cashmere Goat semen pre-served at 4℃and levels of the complete genome DNA methylation, in order to lay a foundation for utilization of ram semen and promotion of artificial insemination technique in the future . MethodFresh semen of ram of Northwest Tibet Cashmere Goat was collected using artificial Vagina. Vitamin C of different concentrations(0,2.0,4.0,6.0,8.0,10.0 and 12.0 mg/mL) were added into the semen 4-time diluted with vitamin B12 and preserved at 4℃for 24 hours. Sperm motili-ty, acrosomal integrity and plasma membrabe integrity were observed and complete genome DNA methylation was detected by real-time fluorescence quantitative PCR. ResultThe Northwest Tibet Cashmere Goat semen after 24 hours preserved at 4℃with 8.0 mg/mL vitamin C showed the best quality. Sperm motility was(73.41±0.47)%, acrosomal integrity(58.89± 0.88)% and plasma membrabe integrity(68.76±0.81)%. The three indexes were higher than those of control which added no vitamin C(P<0.01). At the same time, the level of sperm complete genome DNA methylation was close to that of fresh semen, and significantly lower than those of semen added no vitamin C(P<0.05). ConclusionAdding 2.0 mg/mL vitamin C in Northwest Tibet Cashmere Goat semen preserved at 4 ℃ can reduce the level of DNA methylation and increase the quality of sperm preserved at refrigeration temperature.