The TSP is a classic combinatorial optimization problem. According to the character of the optimal tour of Euclidean plane TSP problem, the sub-path and related notions are presented. A tour construction algorithm is designed by using convex hull, and a genetic algorithm is improved to solve the problem by using Delaunay triangulation diagram as heuristic information. The experimental results in the 144 cities in China and other TSP instances show that the algorithm is effective.