Abstract: A test was designed according to the GB/T 21143-2014 multi sample method, the initiation toughness J_i of 0Cr18Ni9 stainless steel sheet was determined by blunting line method and stretch zone width method, and the test process was monitored by acoustic emission technology. The results show that compared with the blunting line method, the initiation toughness J_i of 0Cr18Ni9 stainless steel sheet measured by the stretch zone width method was closer to the true value. The fracture process of the stainless steel sheet was analyzed according to the acoustic emission test results, and the determined initiation toughness J_i=351.77 kJ·m^-2 by the stretch zone width method.