I have read some introduction about how to create Google Chrome extensions. Is that possible to create the extension using Python instead of JS?
A google chrome extension is simply a webpage with a few extra permissions and so on. So, what you're looking for is basically a method to use python as a scripting language inside a browser.
The problems with this :

Not all browsers are capable of using python as a scripting language
By default javascript scripts are enabled in most browsers, python may not be be.
Not enough tutorials on how to use python here. JS is way more popular.

But returning to how to do it. Popular methods:

Brython - They use HTML5 + text/python scripts to directly embed python inside a browser.
PyJS - here, they actually compile Python into Javascript. Somewhat more complicated, but finally the browser sees JS, so it is usable anywhere.
Can I use python to develop Google Chrome extensions?