The invention relates to a method for preventing shell expansion of a thick and large surface of a precision-casting stainless steel casting. The method comprises the following steps of: 1, manufacturing all layers according to a traditional process till the layer of shell where a thick and large surface of a precision-casting stainless steel casting shell is bundled with iron wires, wherein the layer of shell bundled with iron wires can be any layer between the fourth layer and the antepenult layer and one thick and large surface is bundled with two rounds of iron wires between which the distance is not larger than 70mm; 2, completely covering the bundled iron wires with a pasty fireproof coating, completely filling gaps between the iron wires and previous layer of shell with the fireproof coating, and spreading fireproof sand on the pasty fireproof coating; 3, drying the pasty fireproof coating and the fireproof sand on the iron wires, and then fabricating next layer of shell till subsequent shell fabrication is completed according to process requirements; 4, dewaxing; 5, roasting; and 6, casting the shell. By the method disclosed by the invention, the percent defective of castings, caused by shell expansion, can be reduced to below 1.5% from the original more than 25%, labor load of subsequent process steps can be reduced greatly, and productivity is improved.