A thermally insulating fixture includes a support bracket, and a thermally insulating member mounted on the support bracket. The support bracket has a middle provided with a sheet plate. The sheet plate includes two hollow portions formed on two ends thereof. Each of the two hollow portions is provided with an abutment laminating the sheet plate. The sheet plate is provided with a through hole. The thermally insulating member covers an exterior of the support bracket. In practice, when the self-tapping screw extends through the through hole of the sheet plate and is screwed and tightened, a force is applied on the abutment. Thus, the abutment reinforces the strength of the support bracket to reduce deformation of the support bracket.