Z-shaped　folding　wing　presents　multiple　forms　during　a　flight　and　the　structural　dynamical　feature　varies　with　its　forms.　So　the　research　on　the　modal　characteristics　is　important　to　investigate　its　structure.　First,　the　modal　analysis　technology　and　the　fundamentals　of　PolyMAX　algorithm　are　reviewed.　Then,　modal　experiments　are　conducted　on　the　Z-shaped　folding　wing　at　different　forms　based　on　the　experimental　modal　analysis　(EMA)　and　operational　modal　analysis　(OMA).　Finally,　the　parameters　of　the　first　five　orders　are　validated.　The　results　show　that　folded　angles　have　significant　impact　on　the　structure　stability.　Particularly,　the　structure　is　stablest　when　the　folded　angle　is　90°.　©　2020,　Editorial　Department　of　JVMD.　All　right　reserved.