Emacs org-mode export markdown

After emacs 25,you just need add a line in your emacs configuration file: .emacs

(require 'ox-md nil t)

If you are using Org-mode version 8.0 or later (check with M-x org-version), the export framework is broken up into several libraries that are not necessarily loaded by default.

Something like this in your Emacs configuration can load the Markdown exporter automatically with Org-mode:

(eval-after-load "org"
  '(require 'ox-md nil t))

M-x customize-variable <Ret> org-export-backends <Ret>

check option 'md', then save.