The invention relates to a strain gauge assembly for testing the curing stress of a thermosetting pouring PBX and a testing method thereof. The strain gauge assembly for testing the curing stress of the thermosetting pouring PBX comprises a base material and a strain gauge which is wrapped in the base material, the strain gauge is in a tiling shape in the base material, and the base material is composed of hydroxyl-terminated polybutadiene, dioctyl adipate, aluminite powder, 2 / 4- toluene diisocynate and triphenylbismuthine. The testing method of the curing stress of the thermosetting pouring PBX comprises the steps of calibrating the strain gauge assembly, arranging the strain gauge assembly, pouring an elastic body, and testing the stress in the curing process. The strain gauge assembly can be randomly placed at different positions in the pouring PBX, in the testing process, the compatibility of the base material and chemical slurry is good, the strain gage can not be curled or corroded by liquid chemical slurry due to the protection of the base material, and the testing effect on the curing stress of the pouring PBX is obvious.