uses   Winapi.RichEdit;
// yOffset values
type

 TCharacterFormat = (CFM_Superscript, CFM_Subscript, CFM_Normal);
procedure RE_SetCharFormat(RichEdit: TRichEdit; CharacterFormat: TCharacterFormat);
//=======================================
procedure RE_SetCharFormat(RichEdit: TRichEdit; CharacterFormat: TCharacterFormat);
var
 // The CHARFORMAT structure contains information about
 // character formatting in a rich edit control.
 Format: TCharFormat;
begin
 FillChar(Format, SizeOf(Format), 0);

 with Format do
 begin

   cbSize := SizeOf(Format);
   dwMask := CFM_OFFSET;
   // Character offset, in twips, from the baseline.
   // If the value of this member is positive,
   // the character is a superscript;
   // if it is negative, the character is a subscript.
   case CharacterFormat of
     CFM_Superscript: yOffset :=  250;    //上标偏移值
     CFM_Subscript: yOffset   := -250;    //下标偏移值
     CFM_Normal: yOffset := 0;
   end;

 end;
 // The EM_SETCHARFORMAT message sets character formatting in a rich edit control.
 // SCF_SELECTION: Applies the formatting to the current selection
 Richedit.Perform(EM_SETCHARFORMAT, SCF_SELECTION, Longint(@Format));

end;

procedure TMainForm.ToolButton7Click(Sender: TObject);
begin
RE_SetCharFormat(Editor, CFM_Superscript);    //上标
end;

procedure TMainForm.ToolButton8Click(Sender: TObject);
begin
RE_SetCharFormat(Editor, CFM_Subscript);   //下标
end;