Program.cs里增加这句
UserLookAndFeel.Default.SetSkinStyle("Black");//黑色主题
//有下面这些主题可以选择（具体可以看dev的Demon里）
//"|DevExpress Style|Caramel|Money Twins|DevExpress Dark Style|
//iMaginary|Lilian|Black|Blue|Office 2010 Blue|Office 2010 Black|Office 2010 Silver|
//Office 2007 Blue|Office 2007 Black|Officmetre 2007 Silver|Office 2007 Green|Office 2007 Pink|
//Seven|Seven Classic|Darkroom|McSkin|Sharp|Sharp Plus|Foggy|Dark Side|Xmas (Blue)|
//Springtime|Summer|Pumpkin|Valentine|Stardust|Coffee|Glass Oceans|
High Contrast|Liquid Sky|London Liquid Sky|The Asphalt World|Blueprint|"