There　has　been　considerable　research　conducted　in　recent　years　into　establishing　relationships　between　crashes　and　various　traffic　flow　characteristics　in　foreign　countries,　and　progress　which　has　been　made　in　the　modeling　of　crashes　and　traffic　flow　parameters　was　very　rapid.　Whereas　in　China,　research　in　this　field　is　very　little　due　to　the　difficulty　to　collect　the　crash　data　and　traffic　flow　data,　so　models　about　how　the　traffic　flow　parameters　impact　on　safety　are　vague.　This　study　clarified　the　relationship　between　volume　to　capacity　ratio　(V/C)　and　crash　rate　using　3　years　crash　and　traffic　flow　data　of　a　freeway.　This　relationship　can　be　used　as　a　basic　reference　to　predict　and　prevent　traffic　accidents.　The　hourly　＇crash　rate　model,　having　an　independent　variable　of　hourly　V/C,　was　established　by　regression　analysis,　and　the　relationship　between　V/C　ratio　and　crash　rate　was　represented　by　a　U-shaped　curve.　The　crash　rate　is　higher　in　the　low　hourly　V/C　range,　and　decreases　with　an　increasing　V/C　ratio,　and　then　increases　as　the　V/C　ratio　increases.　When　the　V/C　is　0.58,　the　crash　rate　is　the　lowest.