解决方法：

修改超时时间：

pip --default-timeout=1000 install -U pip

问题如下：

Collecting xlwt

Downloading xlwt-1.3.0-py2.py3-none-any.whl (99kB)

Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.python.org', port=443): Read timed out. (read timeout=15)",)': /simple/xlwt/

Exception:

Traceback (most recent call last):

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 302, in _error_catcher

yield

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 384, in read

data = self._fp.read(amt)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\cachecontrol\filewrapper.py", line 60, in read

data = self.__fp.read(amt)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\http\client.py", line 449, in read

n = self.readinto(b)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\http\client.py", line 493, in readinto

n = self.fp.readinto(b)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\socket.py", line 586, in readinto

return self._sock.recv_into(b)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\ssl.py", line 1009, in recv_into

return self.read(nbytes, buffer)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\ssl.py", line 871, in read

return self._sslobj.read(len, buffer)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\ssl.py", line 631, in read

v = self._sslobj.read(len, buffer)

socket.timeout: The read operation timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\basecommand.py", line 215, in main

status = self.run(options, args)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\commands\install.py", line 335, in run

wb.build(autobuilding=True)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\wheel.py", line 749, in build

self.requirement_set.prepare_files(self.finder)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\req\req_set.py", line 380, in prepare_files

ignore_dependencies=self.ignore_dependencies))

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\req\req_set.py", line 620, in _prepare_file

session=self.session, hashes=hashes)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 821, in unpack_url

hashes=hashes

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 659, in unpack_http_url

hashes)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 882, in _download_http_url

_download_url(resp, link, content_file, hashes)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 603, in _download_url

hashes.check_against_chunks(downloaded_chunks)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\utils\hashes.py", line 46, in check_against_chunks

for chunk in chunks:

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 571, in written_chunks

for chunk in chunks:

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\utils\ui.py", line 139, in iter

for x in it:

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 560, in resp_read

decode_content=False):

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 436, in stream

data = self.read(amt=amt, decode_content=decode_content)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 401, in read

raise IncompleteRead(self._fp_bytes_read, self.length_remaining)

File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\contextlib.py", line 99, in __exit__

self.gen.throw(type, value, traceback)

File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 307, in _error_catcher

raise ReadTimeoutError(self._pool, None, 'Read timed out.')

pip._vendor.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='pypi.python.org', port=443): Read timed out.