Abstract: Haemophilus parasuis （Hps）,a gram-negative bacterium,belongs to Hemophilus of Pasteurellaceae.Hps is the main causative factor of swine hemophilosis.Multilocus sequence typing （MLST） has simple and rapid operation,repeatability,higher resolution and accurate results.Furthermore,the MLST results can be shared and compared by labs via internet.The experiment was performed to introduce the principles,methods and results of MLST technology,which provided a reference for Haemophilus parasuis typing.