To study Proteus.mirabli's (Pm)biological characteristics and possibility of causing disease,biochemical method,ELISA and animal test were used to pathogenically appraise and toxicity test.Pm can grow at pH 10.0 in 10% Nacl,the physiological and biochemical characteristics is normal.Endotoxin was detected in all Pm.ST was found in 2 of them.The Pm could catch mouse a disease and produced heat resistance hemolysin.80% Pms produced superbroad spectrum B lactamase.100% Pm resisted 3 kind of drugs.the Pm was addicted to alkali and resisted salt.