The invention relates to a machining method of a large thin-wall bearing ring. The machining method comprises the steps that 1, pretreatment is carried out, wherein a bearing ring rough body is heated to 180-220 DEG C and kept at the temperature for 10-14 h; 2, the ring is subjected to heat treatment; 3, low-temperature cooling treatment is carried out, wherein the temperature is decreased to -65--75 DEG C and kept for 1.5-2.5 h; 4, rough grinding machining is carried out; 5, primary additional tempering is carried out, wherein the roughly-ground product is heated to 140-160 DEG C and kept at the temperature for 22-24 h; 6, semi-accurate machining is carried out; 7, secondary additional tempering is carried out, wherein the semi-accurate ground product is heated to 140-160 DEG C and kept at the temperature for 22-24 h; and 8, final grinding machining is carried out. By means of the machining method, the factors that before heat treatment, machining stress deformation is caused, quenching stress is too large, and stress cannot be completely released through one-time tempering are eliminated, the problem that large thin-wall bearing parts are large in heat treatment deformation is relieved, bearing size stability is improved, machining stress is sufficiently released, machining precision is improved, and therefore the surface quality and rotating precision of a bearing are improved.