The subthreshold characteristics has been analyzed to investigate the effect of two gate in Double Gate MOSFET using impact factor based on scaling theory. The charge distribution of Gaussian function validated in previous researches has been used to obtain potential distribution in Poisson equation. The potential distribution was used to investigate the short channel effects such as threshold voltage roll-off, subthreshold swings and drain induced barrier lowering by varying impact factor for scaling factor. The impact factor of 0.1~1.0 for channel length and 1.0~2.0 for channel thickness are used to fit structural feature of DGMOSFET. The simulation result showed that the subthreshold swings are mostly effected by impact factor but are nearly constant for scaling factors. And threshold voltage roll-off and drain induced barrier lowering are also effected by both impact factor and scaling factor.