您不能使用标准System.Data.OracleClient作为SYSDBA进行连接，如本文所述:

You can't connect as SYSDBA using standard System.Data.OracleClient, as stated by this post : http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2245591&SiteID=1.

您可以使用ODP .NET(适用于.NET的Oracle数据提供程序)或其他第三方库来实现.如果您打算在.NET上构建严肃的Oracle应用程序，建议您至少看看ODP.NET

You can do that using ODP .NET (Oracle Data Provider for .NET), or other third parties library. If you're planning to build serious Oracle Application on .NET, I suggest you at least look at ODP.NET