Abstract: Up to now，the generation of drilling path by automatic programming system for printed circuit boards （PCB） did not give optimal solution．The problem of optimizing the moving path of NC drilling for PCB can be formulated as a large scale travelling salesman problem （TSP） ，and the goal function is defined as the shortest total time of moving drill．Because TSP is known to be a NP-complete problem，it would be too difficult to tackle it with traditional optimization methods．In this paper，an algorithm of solving TSP for PCB by simulated annealing is presented in detail．Based on the research，an optimal automatic programming system for PCB is developed．