Abstract: In order to investigate the effect of photoperiod control on blood concentration of melatonin （MLT） in Inner Mongolia white cashmere goat during cashmere non-growing period, a total of 12 female Inner Mongolia white cashmere goats with similar age, cashmere production and body weight were selected and allocated to experimental group （short photoperiod, n =6） and control group （normal photoperiod, n=6）. The blood samples were collected from the ewes to determine the MLT concentration, and the differences in blood MLT concentration between experimental group and control group were statistically assessed. The results showed that the higher blood MLT concentration were observed in experimental group at 20：00 （P〈0.05）, 21：40, and 6：40 （P〈0.05） compared to control group, and the duration of the peak concentration of blood MLT was longer in experimental group compared to control group. In October, the variation of blood MLT concentration in experimental group was similar to that in control group, and no significant differences in blood MLT concentration between experimental group and control group were observed （P〉0.05）; for control group, the blood MLT concentration was obviously higher in October compared to June, but the highest value of blood MLT concentration was observed in the ewes receiving short photoperiod treatment. Collectively, these data reveal that the photoperiod regulates the hair follicle development and cashmere growth cycle, and the short photoperiod treatment stimulates the early cashmere growth in the non-growing period in Inner Mongolia white cashmere goat.