Abstract: Organisms obtained from symptomatic pig with clinical signs typical of porcine eperythrozoonosis, were Mycoplasma suis (M. suis), as was confirmed by microscopic examination of Giemsastained peripheral blood smears as well as by PCR. A fragment of 781 bp was amplified and its similarity to a known sequence of M. suis（accession numbers AJ504999）was 99.4％. Continuous culture of the pathogen was established from the infected blood sample. The culture medium was PPLO broth medium supplemented with newborn calf serum, yeast extract, glucose ,etc.. The optimal dilution of red blood cell (RBC), ratio of serum and pH during incubation were evaluated. Cultivation was initiated in an atmosphere containing 5% CO₂ at 37 ℃. The infected RBCs became ghosts with parasites after 72 h of cultivation. No host erythrocyte was supplied in the cultures except initiation. Cultures were maintained in medium ,with a percentage of parasitized erythrocytes（PPE） nearly 100% for more than 280 days. The cultured organisms adhering to ghost was identified to be M. suis on the basis of light and electron microscopic examinations, identical gene sequences, infect negative RBCs test, antibiotics sensitivity test.