In this paper, free vibration analysis of rotating variable thickness annular bladed disk suitable to be used in aircraft gas turbine engine is investigated. The numerical generalized differential quadrature method is introduced in this paper as a fast and efficient numerical method to be used for vibration analysis of bladed disks of real gas turbine engines. The boundary conditions are supposed to be similar to those of the real bladed disk used in the aircraft engines i.e. clamped for the inner edge and free for the outer edge. Considering the thickness of the disk to vary as a power function and the blades of the bladed disk to be rigid, the numerical solution is performed and the effects of thickness variation, geometric parameters, angular velocity, and number of blades on the natural frequencies and critical speeds are investigated. The obtained numerical results are compared with those reported in the literature indicating a good agreement.