This paper presents an analytical solution for the free vibration behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) doubly curved shallow shells with integrated piezoelectric layers.Here,the linear distribution of electric potential across the thickness of the piezoelectric layer and five different types of carbon nanotube (CNT) distributions through the thickness direction are considered.Based on the four-variable shear deformation refined shell theory,governing equations are obtained by applying Hamilton's principle.Navier's solution for the shell panels with the simply supported boundary condition at all four edges is derived.Several numerical examples validate the accuracy of the presented solution.New parametric studies regarding the effects of different material properties,shell geometric parameters,and electrical bound-ary conditions on the free vibration responses of the hybrid panels are investigated and discussed in detail.