from PyPDF2 import PdfReader, PdfWriter

reader = PdfReader("社会心理学 (戴维·迈尔斯,侯玉波) (Z-Library).pdf")
writer = PdfWriter()

for page in reader.pages:
    page.compress_content_streams()  # This is CPU intensive!
    writer.add_page(page)

with open("out.pdf", "wb") as f:
    writer.write(f)