In this paper, we propose an approximate solution to solve the two dimensional potential distribution in ultra-thin body junctionless double gate MOSFET (JL DG MOSFET) operating in the subthreshold regime. Basically, we solved the 2D-Poisson equation along the channel, while assuming a parabolic potential across the silicon thickness, which in turn leads to some explicit relationships of the subthreshold cur- rent, subthreshold slope (SS) and drain induced barrier lowering (DIBL). This approach has been assessed with Technology Computer Aided Design (TCAD) simulations, confirming that this represents an interest- ing solution for further implementation in generic JL DG MOSFETs compact models.