Research on the bacterial predation rate by rumen protozoa was carried out using a technique of fluorescencelabeled bacteria in culture in vitro incubation. Three Xuhuai goats fitted with rumen cannula were used to determine the effects of yucca schidigera extract (YSE) at 0 (group A), 35 (group B) and 70 mg/L (group C) on the determination of bacterial predation rate by rumen protozoa when dietary concentrate to forage ratio was set to 1∶9 in the culture. The results showed that the predation rates of rumen protozoa were 339.9 cells/(cell·h) in group A, 3147 cells/(cell·h) in group B, 339.9 cells/(cell·h) in group C, respectively. It was concluded that the fluorescencelabeled bacteria technique would be a potential option for determination of bacterial predation rate by rumen protozoa.