Abstract: The aim of the present study was to expose the underling mechanisms of the therapeutic effect of cloprostenol on persistent corpus luteum in dairy cows. A total of 16 dairy cows with persistent corpus luteum confirmly diagnosed by rectal examination and uhrasonography examination were randomly assigned to one of two groups such that experimental group （n=10） received cloprostenol treatment and blank control group （n=6） received no treatment. The results revealed that there were significant differences between the total effective rate of the cloprostenol treatment group （90%） and the spontaneous cure rate of blank control group （16.7% ,P〈0.01 ）, indicating that cloprostenol had a specific luteolytic effect and was helpful for the functional recovery of uterus. The morphological changes of corpus luteum and follicle were monitored by ultrasonography examination. The results of the ultrasonography examination demonstrated that during the two days after drug withdrawal, the diameters of the corpus luteum and follicle of the dairy cows in cloprostenol treatment group was obviously decreased and increased, respectively; no obvious changes of corpus luteum diameters of the dairy cows in blank control group were observed during the whole monitoring period.