Castration surgery was accomplished on muskrats (Ondatra zibethicus) to observe the changes in scent gland morphology and musk compositions after castration. Six adult male muskrats were randomly divided into castrated and control groups (3 in each group). The musk in scent glands was drained, and then both testes were removed under general anesthesia. Thirty days after the castration, the muskrats were anesthetized and killed, and the serum and the musk were collected. The testosterone (T) concentration in serum and muskrat musk was detected by enzyme-linked immunosorbent assay (ELISA). The scent glands were collected, and their lengths were measured. The paraffin sections of scent glands were stained by the H.E method, and the diameters of glandular cells were measured. And then, the compositions of muskrat musk were detected by gas chromatography-mass spectrometry (GC-MS). The comparison of differences between the two groups was analyzed with independent-samples T test method using SPSS 20.0. The concentration of testosterone in the serum of the castrated group was significantly lower than that of the control group (t = 5.270, P < 0.01), and the testosterone content of muskrat musk in the castrated group was also significantly lower than that of the control group (t = 3.229, P < 0.05) (Table 1). Morphologically, the lengths of muskrat scent glands in the castrated group and the control group were similar and there was no significant difference (t = 1.243, P > 0.05). Histologically, the Diameter of glandular cells of the castrated group was significantly reduced compared with the control group (t = 9.434, P < 0.01) (Fig. 2). The GC-MS analysis showed that both groups contained three rich compositions: macrocyclics, steroids and fatty acids. Among them, the content of macrocyclics in the castrated group was significantly higher (t =﹣3.084, P < 0.05), while the content of steroids was significantly reduced (t = 3.407, P < 0.05) (Table 2). Thus, the muskrat castration model was established, in which the morphology of the muskrat scent gland cells and the compositions of muskrat musk changed.