Abstract: The purpose of this article was to study the pharmacokinetic characteristics of YZG-331, plasma protein binding and metabolic stability in vivo and in vitro. Plasma and tissue concentrations of YZG-331 were determined in mice and rats after administration by LC-MS/MS analysis orally or intravenously. The plasma protein binding of YZG-331 with human, dog, monkey, rat and mouse were measured by ultrafiltration method. The stability of YZG-331 in animal and human plasma, liver microsomes, intestinal bacteria and artificial gastrointestinal fluid was also investigated in vitro. The results show that YZG-331 was absorbed rapidly in both mice and rats after oral administration, while the absorption and elimination saturation YZG-331 were also observed. The bioavailability of YZG-331 was much higher in male mice (51.2%) than that in female mice (27.7%), however, the bioavailability in male rats (27.1%) was lower than that in female rats (78.7%). YZG-331 was widely distributed in different tissues of mice, especially in certain regains of brain, including thalamus, hippocampi, cortical and striatal. YZG-331 was found to bind to human, dog, monkey, rat and mouse plasma protein in vitro (93.3%-98.9%) without significant concentration dependences and species differences. YZG-331 was stable in animal and human plasma, simulated gastric/intestinal fluid and liver microsomal incubations, except rat liver microsomes and intestinal flora. Therefore, we concluded that:the pharmacokinetics of YZG-331 in mice and rats have gender and species differences; YZG-331 was widely distributed in vivo including brain, the targets of the agent; YZG-331 had a high affinity to plasma protein and was metabolized by rat liver microsomes and intestinal flora.