In this paper, an analytical threshold voltage model is proposed for a cylindrical gate-all-around (CGAA) MOSFET by solving the 2-D Poisson’s equation in the cylindrical coordinate system. A comparison is made for both the center and the surface potential model of CGAA MOSFET. This paper claims that the calculation of threshold voltage using center potential is more accurate rather than the calculation from surface potential. The effects of the device parameters like the drain bias (VDS), oxide thickness (tox), channel thickness (r), etc., on the threshold voltage are also studied in this paper. The model is verified with 3D numerical device simulator Sentaurus from Synopsys Inc.