Abstract: The most common PVC geomembrane specimen used in biaxial tensile tests is a traditional cruciform one characterized by four rectangular clamp arms, intersection of which is connected by a corner fillet. Based on the traditional cruciform specimen, the maximum measured true strain in the central area can only reach 30%, which is far less than the prospective strain level under biaxial tension loads for PVC geomembrane. In order to get a more complete stress-strain curve of this material, a reinforced dumbbell-shaped specimen is designed on the basis of the traditional specimen by means of a coupled method of numerical simulation and experiment verification. The results of verification tests show that this new specimen presents high and evenly-distributed stress and low degree of stress concentration in biaxial tension states. The maximum true strain obtained at failure time can reach 100.4%, indicating that the reinforced dumbbell-shaped specimen can meet the demands of mechanical property research of PVC geomembrane under biaxial tension states.