Abstract: In order to compare the expression differences of miRNAs in follicular fluid of yellow cattle during different physiological periods, the ovaries of cattle were collected and divided into groups according to age and the presence of corpus luteum in ovaries, and divided into young with corpus luteum group, young without corpus luteum group, old with corpus luteum group and old without corpus luteum group. The ovarian follicular fluid of each group was extracted, and the expression level of miRNAs was detected by real-time quantitative PCR, and the expression differences of miRNAs in different physiological states were studied. The results showed that the purity and concentration of miRNAs extracted from different follicular fluid samples were satisfactory. For young yellow cattle, when the young group without corpus luteum was used as the control, the relative expression levels of bta-miR-145, bta-miR-191, bta-miR-21-3 p, bta-miR-381, bta-miR-424-3 p, bta-miR-449 b and bta-miR-873 in follicular fluid of the young with corpus luteum were extremely significant reduce（P＜0.01）, while the relative expression level of bta-miR-505 was not significantly different between the two groups（P＞0.05）. For old yellow cattle, when the old without corpus luteum group was used as the control, the relative expression levels of bta-miR-145, bta-miR-191, bta-miR-21-3 p, bta-miR-381, bta-miR-449 b, bta-miR-505 and bta-miR-873 in follicles fluid of the old with corpus luteum group were extremely significant reduce（P＜0.01）, while the relative expression level of bta-miR-424-3 p was significantly reduce（P＜0.05）. For the yellow cattle with corpus luteum on the ovaries, when the young with luteal group was taken as the control, the relative expression level of bta-miR-449 b in follicular fluid of the old with corpus luteum group was significantly reduce（P＜0.05）, the relative expression levels of bta-miR-145, bta-miR-191, bta-miR-21-3 p, bta-miR-381, bta-miR-424-3 p, bta-miR-505 and bta-miR-873 were extremely significantly reduce（P＜0.01）. For the yellow cattle without corpus luteum on the ovaries, when the young without corpus luteum group was used as the control, the relative expression levels of bta-miR-145, bta-miR-191, bta-miR-381 and bta-miR-873 in the follicular fluid of the old without corpus luteum group were extremely significant reduce（P＜0.01）, the relative expression level of bta-miR-505 was significantly reduce（P＜0.05）, while the expression level of bta-miR-21-3 p was not significantly different between the two groups（P＞0.05）. These results indicated that the expression of miRNAs in follicular fluid was significantly correlated with the physiological state of follicles.