Abstract: In order to compare the effects of different methods of extracting exosomes from the cell supernatant during the reprogramming process of goat mammary epithelial cells, the exosomes in the cell supernatant were extracted by ultra-centrifugal method and kit method. The morphology of exosomes was observed by transmission electron microscopy, and the concentration and particle size of exosomes were detected by nanoflow meter. Western-blot assay was used to detect exosome surface marker protein and its relative expression was analyzed by Image J software. The results showed that both exosomes extracted by ultrafast centrifugation method and kit method had disc-like double-layer membrane structure with clear boundary, but there were other protein particles in exosomes extracted by kit method. The exosomes extracted by ultra-fast centrifugal method were relatively dispersed, and the particle size of exosomes was concentrated between 55-60 nm. The size of exosomes extracted by kit method was more uniform, and the particle size of exosomes was concentrated around 58 nm. The specific markers of exosome surface（CD63 and TSG101 protein） extracted by the two methods were positive. The concentration of exosomes extracted by kit method was significantly higher than that by ultrafast centrifugation method（P＜0.01）, and the relative expression levels of CD63 and TSG101, which were specific markers on the surface of exosomes, were also significantly higher than that by ultrafast centrifugation method（P＜0.01）. These results indicated that exosomes could be extracted from the supernatant of goat mammary epithelial cell reprogramming process by both ultra-centrifuge method and kit method. The difference lies in the higher purity of exosomes extracted by ultra-centrifuge method and the higher concentration of exosomes extracted by kit method.