Abstract: The aim of this study was to prepare and evaluate allitride submicron emulsion injection.The submicron emulsion injection was prepared by high-pressure homogenizer,sterilized by 0.22 μm filter membrane and subsequent sterile-packing.Allitride was determined by HPLC.The physical appearance,pH value,particle size distribution,entrapment efficacy,impurities and the allitride content were used as the indexes to evaluate the stability of allitride submicron emulsion injection.It was shown that the optimized formulation of allitride submicron emulsion injection had stable physical appearance,with mean particle size of 100-150 nm,and the entrapment efficacy of 96.5%.All the indexes kept unchanged after the accelerated stability test and long-time stability test. These results demonstrated the stability of allitride submicron emulsion injection，which established the foundation for improving insoluble allitride stability,reducing the vascular stimulation,and subsequently improving the patient compliance during the clinical use.