The paper proposes a method for analyzing the mechanical properties of flexoelectric materials based on the isogeometric finite element method (IGA-FEM) and polynomial chaos expansion (PCE). The method discretizes the flexoelectric governing equations utilizing the B-spline shape functions that satisfy the continuity requirement to obtain the mechanical properties (electric potential) of the material. To obtain a mechanical property with different input parameters, we choose the truncated pyramid model as the object of study, and use IGA-FEM and PCE to solve different single uncertain parameters, including independent Young’s modulus and uniformly distributed force, and two kinds of flexoelectric constants, respectively. Numerical examples are presented to bear out the accuracy and viability of the proposed methodology.