LanguageTool extension for LibreOffice:

You need to install LanguageTool extension to achieve grammar check in LibreOffice.

Get it from here : https://extensions.libreoffice.org/extensions/languagetool

And HowTo on install extension can be found here : http://www.libreoffice.org/assets/Uploads/EN_Documents/Installingextensions.pdf

Other extensions:

For more alternatives, have a look at this source link:

SOURCE : http://www.techrepublic.com/blog/five-apps/five-libreoffice-extensions-to-help-you-catch-grammar-problems/1280/