A trench-type DMOS device, comprising: a substrate of a first conductive type, the substrate serving as a common drain region; an active region of a second conductive type formed on the substrate; a first dielectric layer formed on the substrate, the first dielectric layer defining a plurality of trenches extending from a surface of the first dielectric layer to an interior of the substrate, the plurality of trenches comprising a first trench located in the active region; conductive material filled in the plurality of trenches; an oxide layer positioned between the conductive material and trench walls of the plurality of trenches; a source electrode region located in the active region and adjacent to the first trench; a second dielectric layer covering the first dielectric layer and the plurality of trenches; and a metallic layer covering the second dielectric layer, wherein the plurality of trenches comprises a second trench, the first trench being in communication with the second trench, and the metallic layer comprises a first electrode region and a second electrode region insulated from each other, the first electrode region is electrically connected to the source electrode region via a first conductive pole which extends through the first dielectric layer and the second dielectric layer, thereby forming a source electrode, the second electrode region is electrically connected to the conductive material in the second trench via a second conductive pole which extends through the second dielectric layer, thereby forming a gate electrode, characterized in that the second trench is located outside the active region. a substrate of a first conductive type, the substrate serving as a common drain region; an active region of a second conductive type formed on the substrate; a first dielectric layer formed on the substrate, the first dielectric layer defining a plurality of trenches extending from a surface of the first dielectric layer to an interior of the substrate, the plurality of trenches comprising a first trench located in the active region; conductive material filled in the plurality of trenches; an oxide layer positioned between the conductive material and trench walls of the plurality of trenches; a source electrode region located in the active region and adjacent to the first trench; a second dielectric layer covering the first dielectric layer and the plurality of trenches; and a metallic layer covering the second dielectric layer, wherein the plurality of trenches comprises a second trench, the first trench being in communication with the second trench, and the metallic layer comprises a first electrode region and a second electrode region insulated from each other, the first electrode region is electrically connected to the source electrode region via a first conductive pole which extends through the first dielectric layer and the second dielectric layer, thereby forming a source electrode, the second electrode region is electrically connected to the conductive material in the second trench via a second conductive pole which extends through the second dielectric layer, thereby forming a gate electrode, characterized in that the second trench is located outside the active region.