[AttributeUsage(AttributeTargets.Field)]
public class EnumDisplayAttribute : Attribute
{
 public EnumDisplayAttribute(string displayStr)
 {
  Display = displayStr;
 }
 public string Display
 {
  get;
  private set;
 }
}

public enum TestEnum
{
 [EnumDisplay("一")]
 one,
 [EnumDisplay("二")]
 two,
 three
}

public static class TestEnumExtentions
{
 public static string Display(this TestEnum t)
 {
  var fieldName = Enum.GetName(typeof(TestEnum), t);
  var attributes = typeof(TestEnum).GetField(fieldName).GetCustomAttributes(false);
  var enumDisplayAttribute = attributes.FirstOrDefault(p => p.GetType().Equals(typeof(EnumDisplayAttribute))) as EnumDisplayAttribute;
  return enumDisplayAttribute == null ? fieldName : enumDisplayAttribute.Display;
 }
}

class Program
{
 static void Main(string[] args)
 {
  TestEnum e = TestEnum.one;
  Console.WriteLine(e.Display());
  TestEnum e1 = TestEnum.three;
  Console.WriteLine(e1.Display());
  Console.ReadKey();
 }
}

一 
three
扩展说明

public class T
{
 public void Get()
 { }
 public int Num { get; set; }
}
T tt = new T();
Console.WriteLine(nameof(tt.Num));
Console.WriteLine(nameof(tt.Get));