Abstract: The surface fitting process is used to treat moire data, and it is an improvement of thetraditional one. From the moire data, a method of measurement of J-integrals is obtained and it can beapplied to pressure vessels and other allied shell structures. By the proposed method, J-integrals of different contours are calculated with ceatrally cracked wide plates under diffe-rent loading conditions. The J-integrals calculated by the proposed method are in goodagreement with those from the Rice formula.