In Google webmaster tools we can change domain.  This tools will transfer all indexed pages to another domain.  I know this technique,  but I have another problem.I have web site that contains multiple keywords.  I need to build another website for one of the same keyword from my site.  For example, web design, and loan software have good ranking for my site.  I need to transfer loan software to a new web site built just about that topic.
How transfer Google index for a single keyword to another domain
google;keywords;ranking;transfer
As far as I know, there is no way to transfer specific keyword from one site to another site, because keywords are indexed by Google according to the content of your site.However, you can create a new site & then redirect all the links that are being indexed for loan software from the old site to the new site. Of course, you'll have to transfer the contents of those links to the new site as well (or at least have very similar contents to the redirected links).That way Google will give some of the ranking points to your new site and index your desired loan software keyword for the new site.However, keep in mind that you may not have the same ranking points in the new site. Since Google SERP ranking may depend on other metrics (e.g. backlinks, Page Rank, authority etc.) that may not be immediately transferable to the new site.