Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

 { Without OLE }

 procedure XlsWriteCellLabel(XlsStream: TStream; const ACol, ARow: Word;
   const AValue: string);
 var
   L: Word;
 const
   {$J+}
   CXlsLabel: array[0..5] of Word = ($204, 0, 0, 0, 0, 0);
   {$J-}
 begin
   L := Length(AValue);
   CXlsLabel[1] := 8 + L;
   CXlsLabel[2] := ARow;
   CXlsLabel[3] := ACol;
   CXlsLabel[5] := L;
   XlsStream.WriteBuffer(CXlsLabel, SizeOf(CXlsLabel));
   XlsStream.WriteBuffer(Pointer(AValue)^, L);
 end;


 function SaveAsExcelFile(AGrid: TStringGrid; AFileName: string): Boolean;
 const
   {$J+} CXlsBof: array[0..5] of Word = ($809, 8, 00, $10, 0, 0); {$J-}
   CXlsEof: array[0..1] of Word = ($0A, 00);
 var
   FStream: TFileStream;
   I, J: Integer;
 begin
   Result := False;
   FStream := TFileStream.Create(PChar(AFileName), fmCreate or fmOpenWrite);
   try
     CXlsBof[4] := 0;
     FStream.WriteBuffer(CXlsBof, SizeOf(CXlsBof));
     for i := 0 to AGrid.ColCount - 1 do
       for j := 0 to AGrid.RowCount - 1 do
         XlsWriteCellLabel(FStream, I, J, AGrid.cells[i, j]);
     FStream.WriteBuffer(CXlsEof, SizeOf(CXlsEof));
     Result := True;
   finally
     FStream.Free;
   end;
 end;

 // Example: 

procedure TForm1.Button2Click(Sender: TObject);
 begin
   if SaveAsExcelFile(StringGrid1, 'c:\MyExcelFile.xls') then
     ShowMessage('StringGrid saved!');
 end;