Abstract A threshold voltage model of the short channel DMOS (Double-Diffusion Metal-Oxide- Semiconductor) is proposed. Based on the 2-D distribution of channel depletion charge, the channel depletion charge is calculated and the mathematical expression of the threshold voltage model of the short channel DMOS is obtained. The results of the model agree well with those of the 2-D simulator MEDICI. The analysis shows that the effect of short channel should be considered when the channel length is less than 0.80μm.