Here I describing how to add google recaptcha in admin login in wordpress.
Adding a Google ReCaptcha checkbox to your WordPress login screen denies access to automated scripts while making it easy on humans to log in by checking a box. As Google says, it is “Tough on bots, easy on humans.”.
Many Worpdress sites are bombarded by automated scripts trying to log in to the admin over and over.
The No Captcha is a very simple, Google-supported test to quickly deny access to automated scripts. It is great by itself to instantly make your WordPress site more secure, or can be used with other plugins (like Google Authenticator, Limit Login Attempts, etc.) as part of a defense-in-depth strategy.
I've gone to great lengths to try to make sure this plugin is easy to use and install, that it is compatible with different WordPress configurations, supports multiple languages, and that you won’t accidentally lock yourself out of the admin by using it. I use it myself on my own sites as well. So far, it just works.