Abstract: A raster algorithm of minimum spanning tree in space with obstacles is described.Firstly,with the idea of zero initialization,location data,including entity point,obstacle point and ordinary spatial point,are initialized.Secondly,the nearest connected graph in space with obstacles,also known as the Delaunay graph,is gained by trace back algorithm on the basis of Voronoi graph.Lastly,minimum spanning tree is gained by greedy strategy according to the nearest connected graph.