On　the　basis　of　the　principle　of　real-time,　user　transparence,　keeping　spatial　awareness　during　the　design　of　collision　detection　scheme,　this　paper　proposed　a　new　horizontal　collision　detection　scheme　TMBHDCD　based　on　two-level　2D　projection　maps　and　described　the　implementation　and　the　system　architecture.　It　adopted　2-level　projection　maps　which　were　Free　Space　Map　and　Detail　Projection　Map　to　locate　2D　position　of　avatar　during　collision　detection;　and　was　divided　the　processing　flow　of　collision　detection　into　three　phases:　collision　detecting,　collision　avoidance　and　path　amendment;　introduces　collision　precaution　field,　collision　repulsive　field　and　collision　repulsive　zone　for　moving　obstacle　to　implement　collision　detecting,　avoidance　and　adjustment　combined　with　Detail　Projection　Map.