Environment　exploration　and　map-building　are　one　of　the　fundamental　robotic　application　researches.　An　appropriate　navigation　algorithm　can　facilitate　robots　to　map　the　environment　within　shorter　time.　A　real-time　navigation　algorithm　based　on　virtual　centrifugal　force　is　proposed　in　this　paper　for　a　robot　to　implement　on-line　exploration　of　an　unknown　environment　in　real　time,　and　collision　between　a　robot　and　an　obstacle　can　be　avoided　with　the　VCF　algorithm.　The　wall-following　strategy　is　one　of　the　special　cases　of　the　proposed　algorithm　when　the　robot　approaches　an　obstacle.　Simulation　experiments　are　implemented　to　verify　the　effectivity　of　the　proposed　algorithm.