Abstract: An in-plane corrugated trapezoidal cellular supporting structure applied to flexible telescopic sandwich skin of morphing wing was proposed. By analyzing the in-plane scaling properties of the supporting structure, the relationship between the in-plane transverse dimensionless equivalent elastic modulus and the three parameters (shape coefficient k, width coefficient t and height coefficient h) was obtained.The equivalent elastic modulus decreases with the increase of k or h, and increases with the increase of t. Finite element analysis were carried out with ANSYS software, and the in-palne mechanical characteristics were demonstrated through experiment. The results show that the theoretical analysis and finite element analysis was basically consistent with the experimental results. By selecting appropriate structure parameters, the in-plane transverse equivalent elastic modulus can be as low as 10^-4 of the raw material, smaller than the accordion cellular supporting structure with the same parameters, which means that the trapezoidal cellular has stronger ability of transformation. Compared with traditional support structures, this structure may reduce the driving force required and energy consumed during morphing, and improve the morphing efficiency of the flexible skin.