In　order　to　reflect　the　influence　of　traffic　accident　delay　on　route　choice　for　traveler　reasonably,　traffic　accident　delay　model　under　random　state　was　put　out.　The　uncertain　factors　of　traffic　accident　such　as　randomness,　duration　and　road　capacity　were　introduced　into　traffic　assignment　model,　and　the　route　choice　model　was　modified.　The　maximum　preponderant　travel　range　of　each　grade　road　was　analyzed.　According　to　the　modified　route　choice　model,　successive　traffic　assignment　method　was　adopted.　The　turnovers　and　travel　distances　of　all　grade　roads　were　got,　and　the　travel　distances　were　compared　with　the　travel　distances　while　traffic　accident　delay　was　not　considered.　Analysis　result　shows　that　while　traffic　accident　delay　is　considered,　the　maximum　travel　distances　of　brunch,　secondary　primary　road,　main　road　and　expressway　are　2.000,　2.946,　4.054　and　5.963　km　respectively.　While　traffic　accident　delay　is　not　considered,　the　maximum　distances　of　those　roads　are　2.000,　3.000,　6.000　and　10.000　km　respectively.　Traffic　accident　delay　is　the　significant　factor　for　traveler　route　choice.　While　traffic　accident　delay　is　considered,　the　maximum　travel　distances　of　higher　grade　roads　decrease.　Compared　with　the　conventional　route　choice　models,　the　proposed　model　is　better.