In order to apply carbon nanotube field effect transistor (CNTFET) to circuit simulation, maintaining an acceptable accuracy while minimizing computation time is a major problem. To establish a simple and high accuracy CNTFET model in HSPICE, based on the semi-classical model of CNTFET, the relationship between self-consistent electric potential and carrier density is analyzed, linear approximation is used for curve fitting, and explicit expression of self-consistent electric potential is deduced, so that the iterative solution of an integral equation is avoided. Then the CNTFET model in HSPICE is built. Simulation demonstrates that the proposed model can maintain high accuracy, and the logic functions can be realized in corresponding logic gates built with the proposed model, while the computation time is significantly reduced.