The　foggy　freeway　is　a　scenario　with　a　high　incidence　of　accidents.　Different　traffic　flow　conditions　will　affect　the　driving　behavior　of　conditionally　autonomous　vehicle　drivers　in　the　foggy　areas　of　the　freeway.　In　this　study,　the　experiment　was　carried　out　by　using　the　driving　simulation　system.　Forty-two　participants　drove　on　a　foggy　freeway　according　to　two　traffic　conditions　and　two　non-driving　related　tasks.　Wilcoxon　Signed-Rank　Test　and　Survival　Analysis　were　applied　to　explore　the　impact.　The　results　show　that　the　effects　of　different　non-driving　related　tasks　on　driving　behavior　are　mainly　concentrated　in　the　takeover　process;　The　deceleration　reaction　time　of　the　free　flow　(6.04　s)　is　much　lower　than　that　of　bound　flow　(9.40　s);　In　the　condition　of　bound　flow,　the　driver　is　more　inclined　to　slow　down　without　braking.　Potential　application　areas　of　this　research　comprise　safety　assessment　of　conditional　autonomous　driving　and　formulating　autonomous　driving　policy.