Objective: To study the role of auto-antibody in the diagnosis of patients with PBC. Methods: ANA, SMA and AMA in serum of 58 PBC patients were tested by indirect immune fluorescence and Western blot. Such auto-antibodies as Anti-type AMAM2,anti-SLA/LP, anti-LKM-1 and anti-LC-1 were also identified. Results: Auto-antibodies existing in patients with PBC were mainly AMA(96.5%) and AMAM2(93.1%) and the titer was beyond 1∶100. 8 cases of those patients were positive with ANA and SMA simultaneously. One case had positive AMA and SLA/LP in serum and the clinical appearances were the same as those of type Ⅰ and type Ⅲ autoimmune hepatitis. 19 patients with positive AMAM2 in serum had liver-puncture and the results suggested the diagnosis of PBC in 63.7%(12/9). Conclusion: Test of auto-antibodies is clinically significant for the diagnosis of autoimmune hepatitis.