An　audio　navigation　system　is　a　very　useful　tool　for　driving　path　guidance　with　less　distraction.　However,　the　influence　of　the　audio　navigation　system　on　driver　behavior,　especially　in　complicated　road　environments,　is　still　not　entirely　clear.　This　study　aims　to　investigate　navigation　prompt　timing　(NPT),　navigation　prompt　message　(NPM),　and　their　combination　in　an　audio　navigation　system　on　driving　behavior　on　an　urban　expressway　with　five　exits.　Driving　simulator　technology　was　used　to　reproduce　the　experimental　environment　and　obtain　driver　behavior　data.　Four　indicators-speed,　standard　deviation　of　speed,　absolute　values　of　acceleration,　and　depth　of　accelerator-were　selected　to　examine　the　main　and　interactive　effects　of　NPT,　NPM,　and　their　combination　based　on　repeated　measures　analysis　of　variance.　The　results　show　that　the　driver＇s　psychological　state　and　operation　of　the　vehicle　on　the　urban　expressway　were　affected　by　the　prompt　timing　and　messages　of　the　audio　navigation　system.　An　interaction　effect　existed　between　prompt　timing　and　prompt　messages　of　the　system,　and　this　effect　adjusted　the　effect　on　the　driver＇s　psychological　state　and　vehicle　operation　caused　by　these　two　important　factors.　This　study　contributes　to　our　understanding　of　the　influence　of　audio　navigation　systems　on　driver　behavior　in　complex　road　environments　and　thus　lays　a　foundation　for　developing　standard　audio　navigation　broadcast　guidelines　to　improve　drivers＇　acceptance　of　navigation　systems,　reduce　drivers＇　cognitive　workload,　and　improve　the　level　of　vehicle　operation　safety.