def save_file(self):
    filename = (QFileDialog.getSaveFileName(self, 'Сохранить', '', ".xls(*.xls)"))
    wbk = xlwt.Workbook()
    sheet = wbk.add_sheet("схема", cell_overwrite_ok=True)
    self.s_f(sheet)
    wbk.save(filename)

def s_f(self, sheet):
    for currentColumn in range(self.table.columnCount()):
        for currentRow in range(self.table.rowCount()):

            my_icon = self.table.item(currentRow, currentColumn)
            sheet.write(currentRow, currentColumn, str(my_icon or ''))

def open_file(self):
    filename = QFileDialog.getOpenFileName(self, 'Открыть', '', '.xls(*.xls)')

    book = xlrd.open_workbook(filename)
    sheet = book.sheet_by_index(0)
    data = [[sheet.cell_value(r, c)for c in range(sheet.ncols)]for r in range(sheet.nrows)]

    for row, columnvalues in enumerate(data):
        for column, value in enumerate(columnvalues):
            item = QTableWidgetItem()
            item.setData(Qt.DisplayRole, str(value))
            self.table.setItem(row, column, item)