Aiming　at　the　problems　in　unknown　environment　for　mobile　robots　path　planning,　a　dynamic　growing　self-organizing　map　with　A*　(DGSOM_A*)　algorithm　was　proposed　and　used　in　the　map　building　and　path　planning.　Firstly,　the　method　used　a　two-dimentional　simulation　software　Mobotsim　to　obtain　environmental　information　samples　for　DGSOM_A*　by　moving　the　robot　without　collision,　and　then　built　the　environment　map　through　continuously　increasing　the　new　SOM　neurons　with　the　robot　movement,　thus　generated　the　topology　map　to　describe　the　environment　information　with　a　few　SOM　neurons.　Finally,　it　completed　navigation　by　finding　an　optimal　path　from　the　start　point　to　the　target.　The　experimental　results　show　that　the　proposed　DGSOM_A*　method　detects　the　complex　desktop　environment　effectively　and　correctly　and　the　robot　can　realize　environment　mapping　automatically　by　comparing　to　the　SOM　algorithm.