Based on surrounding-gate schottky barrier metal-oxide semiconductor field transistor (MOSFET) structure, the distribution of surface potential is obtained by solving two-dimensional Poisson equation in cylindrical coordinates, and the threshold voltage model of surrounding-gate schottky barrier NMOSFET which is applicable to the low voltage of drain is built. According to the calculation results, the dependences of threshold voltage and drain-induced barrier-lowering on voltage of drain, channel radius and channel length are studied in detail, which can provide some reference for the design of surrounding-gate schottky barrier MOSFET device and circuit.