我也很想知道。我遇到了同样的问题。

range.SetNumberFormat(COleVariant("@"));
Eg:
void CCDlg::OnOK() 
{
try
{
_Application app;     // app is an _Application object.
_Workbook book;       // More object declarations.
_Worksheet sheet;
Workbooks books;
Worksheets sheets;
Range range;          // Used for Microsoft Excel 97 components.
LPDISPATCH lpDisp;    // Often reused variable.
COleVariant
covTrue((short)TRUE),
covFalse((short)FALSE),
covOptional((long)DISP_E_PARAMNOTFOUND, VT_ERROR);
if(!app.CreateDispatch("Excel.Application"))
{
AfxMessageBox("Couldn't CreateDispatch() for Excel");
return;
}
app.SetVisible(TRUE);
lpDisp = app.GetWorkbooks();     // Get an IDispatch pointer.
ASSERT(lpDisp);
books.AttachDispatch(lpDisp);    // Attach the IDispatch pointer
// to the books object.
lpDisp = books.Open("C:\\temp\\book1.xls",     // Test.xls is a workbook.
covOptional, covOptional, covOptional, covOptional, covOptional,
covOptional, covOptional, covOptional, covOptional, covOptional,
covOptional, covOptional );   // Return Workbook's IDispatch
// pointer.
book.AttachDispatch( lpDisp );
lpDisp = book.GetSheets();
ASSERT(lpDisp);
sheets.AttachDispatch(lpDisp);
// Get sheet #1 and attach the IDispatch pointer to your sheet
// object.
lpDisp = sheets.GetItem( COleVariant((short)(1)) );                                       
ASSERT(lpDisp);
sheet.AttachDispatch(lpDisp);

lpDisp = sheet.GetRange(COleVariant("B2"), COleVariant("b6"));
range.AttachDispatch(lpDisp);
range.SetNumberFormat(COleVariant("@"));
range.SetItem(COleVariant((long)(1)),COleVariant((long)(1)),COleVariant(LPCTSTR("000666"))); 


// Release dispatch pointers.
range.ReleaseDispatch();
sheet.ReleaseDispatch();
// This is not really necessary because
// the default second parameter of AttachDispatch releases
// when the current scope is lost.

} // End of processing.

catch(COleException *e)
{
        char buf[1024];     // For the Try...Catch error message.
        sprintf(buf, "COleException. SCODE: %08lx.", (long)e->m_sc);
        ::MessageBox(NULL, buf, "COleException", MB_SETFOREGROUND | MB_OK);
}

catch(COleDispatchException *e)
{
        char buf[1024];     // For the Try...Catch error message.
        sprintf(buf,
"COleDispatchException. SCODE: %08lx, Description: \"%s\".",
(long)e->m_wCode,(LPSTR)e->m_strDescription.GetBuffer(512));
        ::MessageBox(NULL, buf, "COleDispatchException",
MB_SETFOREGROUND | MB_OK);
}

catch(...)
{
        ::MessageBox(NULL, "General Exception caught.", "Catch-All",
MB_SETFOREGROUND | MB_OK);
}    
CDialog::OnOK();
}

原来是range.SetNumberFormat(COleVariant("@"));

谢谢了.