A new channel routing model

while allows horizontal and vertical wire seg-ments to be placed on both layers

and two wires on different layer can be overlapped

is pre-sented. Based on this model

the constraints as well as the rules to layer assignment and routing order of nets in the two-layer channel routing are obtained. Then the property of opti-mal overlapping in a zone is analysed. By means of this property

the algorithm determines layer assignment and routing order of nets acoording to global optimat analysis. The routing area and number of vias are reduced much more than the router based on traditional Gv

Gh graph model. Preliminary experimental results are very encouraging. For the famous Deutsch’s difficult example

the algorithm obtains 18 tracks solution.