Metasurface　enables　a　new　class　of　＂meta-optics＂　that　can　manipulate　light　at　subwavelength　scale.　Despite　that　versatile　metasurfaces　have　been　demonstrated　based　on　a　wide　range　of　materials,　the　vulnerability　of　conventional　materials　to　harsh　environments,　i.e.,　low　resistance　to　corrosion,　low　transparency　at　short　wavelength,　and　lack　of　thermal/mechanical　stability,　greatly　limit　their　applications　in　extreme　conditions.　Diamond　is　well-known　for　exceptional　properties,　including　the　highest　thermal　conductivity,　high　damage　resistance,　extraordinary　hardness,　and　chemical　inertness.　Therefore,　diamond　based　metasurface　is　generally　expected　to　benefit　from　its　material　merits　for　extreme　use.　However,　the　performance　of　diamond　metasurface　in　harsh　environments　remains　unexplored　up　to　date.　To　address　this　question,　this　work　is　designed　to　study　the　suitability　of　single-crystal　diamond　based　metasurface　for　broadband　applications　under　harsh　environments.　As　an　example,　diamond　metasurfaces　with　representative　functionalities,　including　holographic　wavefront-shaping,　DUV-focusing,　are　investigated　under　high-temperature,　acid/alkali,　and　abrasive　conditions,　respectively.　The　findings　prove　the　capability　of　diamond　metasurfaces　for　applications　in　broadband　and　harsh　conditions,　which　not　only　provides　a　practical　and　scalable　scheme　to　encode　on-demand　functionalities　into　diamond,　but　also　unlocks　a　capable　candidate　to　develop　robust,　large　bandwidth,　and　durable　meta-optics　for　advanced　wavefront　shaping　under　extreme　conditions.　Diamond　metasurfaces　with　representative　functionalities,　including　holographic　wavefront-shaping,　DUV　focusing,　are　realized　and　investigated　under　harsh　environment,　including　high-temperature,　acid/alkali,　and　abrasive　conditions,　respectively.　The　results　prove　the　capability　of　diamond　metasurfaces　for　modulations　of　complex　wavefront　in　broadband　and　harsh　conditions,　unlocking　a　capable　candidate　to　develop　robust,　large　bandwidth,　and　durable　meta-optics　for　advanced　wavefront　shaping　under　extreme　conditions.　image