一、实现代码

import PyPDF2
from PyPDF2 import PdfWriter
from PyPDF2.generic import AnnotationBuilder

# 指定输入和输出pdf
pdf_path = r'C:\Users\ASUS\Desktop\temp\xxxx.pdf'
out_path = r'C:\Users\ASUS\Desktop\temp\xxxx2.pdf'

# 创建 PdfWriter 对象
writer = PdfWriter()

with open(pdf_path, 'rb') as pdf_file:
    # 创建 PdfReader 对象
    reader = PyPDF2.PdfReader(pdf_file)

    # 获取 PDF 的总页数
    num_pages = len(reader.pages)

    # 指定页码左下角坐标(x,y)
    x = 280
    y = 30
    # 指定方框的长和宽
    a = 40
    b = 20

    # 逐页添加页码
    for page_num in range(num_pages):
        # 获取指定页的页面对象
        page = reader.pages[page_num]
        pagenum = page_num + 1

        # 添加当前页到 PdfWriter 对象
        writer.add_page(page)

        # 添加页码注释
        annotation = AnnotationBuilder.free_text(
            f" {pagenum}/{num_pages} ",
            rect=(x, y, x + a, y + b),
            font="宋体",
            font_size="10pt"
        )
        writer.add_annotation(page_number=page_num, annotation=annotation)

        # 获取页面内容并打印
        print(f"已经成功镶嵌页码：{page_num + 1}")

# 将最终的 PdfWriter 对象写入文件
with open(out_path, "wb") as fp:
    writer.write(fp)

print("处理完毕")

二、坐标讲解

 # 指定页码左下角坐标(x,y)
    x = 280
    y = 30
    # 指定方框的长和宽
    a = 40
    b = 20

三、实现效果

处理后的PDF，每页都有页码显示