This　paper　discusses　the　method　of　constructing　a　node-path-net　for　mobile　robot　by　using　Voronoi　diagram　theory　in　detail.　It　also　optimizes　the　node-path-net　and　resolves　some　problems　of　the　net.　Then　high　efficient　A*　algorithm　is　adopted　to　increase　the　efficiency　of　shortest　path　self-searching　of　mobile　robot　between　the　source　and　destination　under　a　vast　environment　or　a　complicate　environment.　Finally,　the　paper　uses　DELPHI　to　simulate　best　path　self-searching,　and　result　shows　that　it　is　completely　feasible　to　make　the　robot　to　find　a　best-path　itself　efficiently　according　the　improved　node-path-net　based　on　Voronoi　by　using　the　A*　algorithm.