Now there are so many JS based MVC framework such as Knockout.j, Backbone.js, but seems most of them are not SEO friendly which can be easily indexed by Google.
Am I missed framework which support SEO by default?
You cannot have a pure JavaScript web-app (i.e. the server is API-only) until search engines learn to index JS apps.
However, if you can share view templates between server and client, that will lift the larger part of the burden of having a non-JS version. You can use any JS framework you like.
Mustache, for example, has implementations for many languages (Ruby, PHP, and JS), and can be easily used from JavaScript.
The Pipe Dream of Sharing Code between Node and the Browser talk explores the possibility of sharing routing, controller, template, and even model code code between Node.js and Backbone.js, with a concept demo on GitHub.
If you are just looking into building some simple AJAX with non-JS fallback, you might want to look into jquery-pjax that uses the new pushState API for nice URLs:
It's ajax with real permalinks, page titles, and a working back button that fully degrades.