[Background] Oxytropis glabra DC.with whole plant toxin is one of locoweed and it widely distributes in the western region of Inner Mongolia.Grazing livestocks cause chronic poisoning after feeding.The primary toxicant that Oxytropis glabra DC.causes livestock poisoning is swainsonine (SW).The study investigates toxicated mechanism of Oxytropis glabra by detecting liver α-mannosidase gene relative expression in different time of mice drenched different doses of SW.[Methods] The animal tissue total RNA kit method for the extraction of total RNA of liver;the microplate method for the determination of RNA purity;the gel electrophoresis for the determination of RNA integrity and the real-time quantitative PCR for the detection of α-mannosidase gene transcription.[Results] Each experimental group and the control group of α-mannosidase gene were expressed, but the transcript expression levels of different groups are different.Compared with the control group, low dose SW can promote liver α-mannosidase gene expression, and the promoting results are more obvious with the test conducting.High and middle dose SW can also improve the α-mannosidase gene relative expression at the initial stage, but it can severely inhibit α-mannosidase gene expression over a long period of time and the inhibiting results are more obvious with the test conducting.[Conclusion] Low dose SW can promote liver α-mannosidase gene expression.However, high and middle dose SW can inhibit it.So Oxytropis glabra DC.produces toxic effect.