Hey there, let's get straight to the core of why you're hitting this error and how to fix it.

The key issue here is PyQt5 does not support Python 2.7 at all. PyQt5 was built exclusively for Python 3.x from its initial release, and since Python 2.7 reached end-of-life back in January 2020, all major libraries (including PyQt) have long dropped support for it. That's exactly why pip throws the "No matching distribution found" error—there are zero PyQt5 builds available for Python 2.7.

可行的解决方案 #

• Upgrade to Python 3.x (Highly Recommended)
  This is the best long-term fix. Not only will you be able to install PyQt5 smoothly with pip install pyqt5, but you'll also gain access to security updates, new features, and ongoing support for both Python and PyQt5. Python 2.7 is no longer maintained, so moving to 3.x is a critical step for any project's stability.

• Install PyQt4 if you must stick with Python 2.7
  If upgrading Python isn't feasible for your project right now, PyQt4 is the official Qt binding that supports Python 2.7. You can try installing it with:

  pip install PyQt4
  

  Keep in mind that PyQt4 is also no longer actively maintained, but it's the only official option for Python 2.7. If pip can't locate it, you might need to use pre-built binary packages from trusted community sources or build it from source (though building from source can be more complex).

内容的提问来源于stack exchange，提问作者user10940555