Using the right Emacs Version

I failed to preview LaTeX with emacs-plus. If you have installed d12frosted/emacs-plus, uninstall it and use emacs-mac.

brew tap railwaycat/emacsmacport
brew install emacs-mac

If you like the fancy spacemacs icon, install it with cask: brew cask install emacs-mac-spacemacs-icon

Install Tex

Emacs settings

Now you can see the rendered LaTeX equation by calling org-preview-latex-fragment or using shortcut ,Tx.

If you want to load LaTeX previews automatically at startup, add this at the beginning of org file: #+STARTUP: latexpreview.