Railway　operation　in　desert　areas　faces　unique　challenges　due　to　wind-blown　sand　penetration　on　the　safety　of　the　line.　In-depth　research　on　the　impact　of　wind-blown　sand　penetration　on　the　shear　performance　of　the　railway　ballast　is　crucial　for　understanding　potential　problems　in　sandy　railways　and　formulating　effective　maintenance　strategies.　This　paper　conducts　a　series　of　direct　shear　tests　under　various　sand　contents　and　load　conditions　using　an　independently　developed　automatic　control　loading　direct　shear　test　apparatus　suitable　for　railway　ballast.　By　accurately　considering　the　interaction　between　sand　and　ballast　particles,　some　direct　shear　numerical　models　of　different　sand-containing　ballast　boxes　based　on　refined　particle　simulation　are　established　based　on　the　discrete　element　method　(DEM)　and　particle　scaling　method,　exploring　the　variation　in　shear　strength,　shear　deformation,　contact　relationships,　and　rotational　characteristics　of　railway　sand-containing　ballast　from　macroscopic　and　microscopic　perspectives.　The　results　show　that　with　the　increase　in　shear　strain,　the　shear　stress　of　the　ballast　with　various　sand　contents　increases　first　and　then　tends　to　stabilize,　and　the　phenomenon　of　dilation　occurs　in　all　cases.　When　the　normal　load　is　constant,　the　shear　strength　and　cohesion　of　the　ballast　show　a　trend　of　first　decreasing　and　then　increasing　with　the　increase　in　sand　content.　The　wind-blown　sand　penetration　inhibits　the　rotational　deformation　during　shearing,　enhancing　particle　aggregation.　With　the　increase　in　sand　content,　the　contact　coordination　number,　powerful　force　chain　number,　and　total　force　chain　number　all　increase　continuously.　However,　the　average　contact　force　shows　a　trend　of　gradually　decreasing　and　then　increasing.　This　study　provides　theoretical　support　and　experimental　backing　for　the　operation　and　maintenance　of　the　ballast　bed　in　sandy　railways.