In view of the errors existing in the system affecting the stability of 2D polygon set operation,an algorithm of realizing the 2D polygon set operation was outlined,and five key measures were given to improve the stability of the algorithm.

Based on the description of graph area and direction of the basic graph element, and by introducing the nodical eigenvalue conception, the polygon operation in mining CAD system was studied in great detail.

A new idea of searching sections in network based on set operation and its valid algorithm

Then,the new single solid was generated by using the set operation between the joint instance and the single solid.

The set operation of 2D drawings (union, intersection and subtraction) is an important foundation of design and hiding of 2D drawings, modeling of mechanical parts and generation of the tool path.

On the basis of analysis and research of Dijkstra algorithm and its application,this paper launches a new solution which does not depend on the forming of static graph structure,but applies the idea of set calculation to get the set which meets the requirement of t.