from openpyxl import Workbook



wb = Workbook()
ws = wb.active
# 需要合并的左上方和右下方单元格坐标
ws.merge_cells(range_string='A1:B3')
ws.merge_cells(start_row=5, start_column=4, end_row=8, end_column=8)

# 单元格取消合并使用unmerge_cells
ws.unmerge_cells(range_string='A1:B3')
ws.unmerge_cells(start_row=5, start_column=4, end_row=8, end_column=8)

常用合并merge_cells和取消合并unmerge_cells方法调用示例。

转载：openpyxl单元格合并_BDawn的博客-CSDN博客_openpyxl合并单元格

openpyxl的单元格合并会把合并区域左上角单元格的值赋给合并之后的单元格，如果这个单元格没有值，即使区域内其他单元格有值，合并后的单元格也是空白
下面写了一个函数用来解决这个问题，这个函数会合并单元格并且将合并区域最上边最左边有值的单元格赋值给合并后的单元格

from openpyxl import Workbook
from openpyxl.utils import get_column_letter

def merge_cells_value(sheet=None, range_string=None, start_row=None, start_column=None, end_row=None, end_column=None):
    """
        将靠上靠左的单元格的value赋值给合并后的单元格
    """
    if start_row > end_row:
        fmt = "{end_row} must be greater than {start_row}"
        raise ValueError(fmt.format(start_row=start_row, end_row=end_row))
    if start_column > end_column:
        fmt = "{end_column} must be greater than {start_column}"
        raise ValueError(fmt.format(start_column=start_column, end_column=end_column))
    if range_string is None:
        fmt = '{start_column}{start_row}:{end_column}{end_row}'
        range_string = fmt.format(start_row=start_row,
                                  start_column=get_column_letter(start_column),
                                  end_row=end_row,
                                  end_column=get_column_letter(end_column))

    v = None
    for cells in sheet[range_string]:
        for cell in cells:
            if cell.value is not None:
                v = cell.value
                break
        if v is not None:
            break
    print(range_string)
    sheet.merge_cells(range_string=range_string)
    sheet['{0}{1}'.format(get_column_letter(start_column), str(start_row))] = v
# 使用方式

wb = Workbook()
ws = wb.active

merge_cells_value(sheet=ws, start_row=5, start_column=4, end_row=8, end_column=8)