This paper investigates the impact of random dopant fluctuation effect on surrounding gate MOSFET, from atomic statistical simulation of device to circuit performance evaluation. The doping profile is generated by an analysis of each lattice atom and then the threshold voltage variation is obtained by device Drift-Diffusion simulation. Then the circuit performance evaluation is performed by feeding the result into a surrounding-gate MOSFET model. It is shown that a significant fluctuation in threshold voltage is due to the decreasing volume. The circuit simulation results also reveal that a surrounding gate MOSFET based 6-T SRAM presents a promising resistibility to noise disturbance.