We report deriving a compact model for CNTFETs, using modified current- voltage relations, commonly used in modeling of CNTFETs. A carbon nanotube with 1.7 nm diameter and 5 nm length has been simulated with a layer of ZrO2 as oxide layer. The thickness of the oxide layer has been considered to be 2 nm. Density of states as a function of Fermi level is considered quadratic for both subthreshold and saturation regime. In this paper, the CNTFET drain current and energy level is derived analytically. Finally, the variation of CNTFET drain current versus gate-source and drain-source voltages will be presented though simulation.