谢谢.我相信一个完整的例子可能对其他有同样问题的人有好处:

Thank you. I believe that a complete example could be good for anyone else who have the same issue:

import pandas as pd
import numpy as np

path = r"C:UsersfedelDesktopexcelDataPhD_data.xlsx"

x1 = np.random.randn(100, 2)
df1 = pd.DataFrame(x1)

x2 = np.random.randn(100, 2)
df2 = pd.DataFrame(x2)

writer = pd.ExcelWriter(path, engine = 'xlsxwriter')
df1.to_excel(writer, sheet_name = 'x1')
df2.to_excel(writer, sheet_name = 'x2')
writer.save()
writer.close()

这里我生成了一个excel文件，根据我的理解，它是通过xslxwriter"还是openpyxl"引擎生成的并不重要.

Here I generate an excel file, from my understanding it does not really matter whether it is generated via the "xslxwriter" or the "openpyxl" engine.

当我想在不丢失原始数据的情况下写入时

When I want to write without loosing the original data then

import pandas as pd
import numpy as np
from openpyxl import load_workbook

path = r"C:UsersfedelDesktopexcelDataPhD_data.xlsx"

book = load_workbook(path)
writer = pd.ExcelWriter(path, engine = 'openpyxl')
writer.book = book

x3 = np.random.randn(100, 2)
df3 = pd.DataFrame(x3)

x4 = np.random.randn(100, 2)
df4 = pd.DataFrame(x4)

df3.to_excel(writer, sheet_name = 'x3')
df4.to_excel(writer, sheet_name = 'x4')
writer.save()
writer.close()

这段代码可以完成工作！

this code do the job!