It's odd. The value of org-file-apps-defaults-gnu is:

((remote . emacs) (system . mailcap) (t . mailcap))

And I checked my local mime file, which shows google-chrome is the default app to open html files:

$ cat ~/.local/share/applications/mimeapps.list 
[Added Associations]
application/epub+zip=FBReader.desktop;
application/pdf=pdf.desktop;
application/vnd.rn-realmedia=smplayer.desktop;
application/x-matroska=smplayer.desktop;
application/x-mimearchive=firefox.desktop;
application/x-ole-storage=libreoffice-impress.desktop;
audio/mpeg=audacious.desktop;
text/html=google-chrome.desktop;
video/mpeg=gnome-mplayer.desktop;
x-scheme-handler/mailto=google-chrome.desktop;KMail2.desktop;

[Default Applications]
text/html=google-chrome.desktop
x-scheme-handler/mailto=google-chrome.desktop

Any idea?

On Mon, Feb 4, 2013 at 4:29 PM, Bastien <bzg@altern.org> wrote:
zhenjiang xu <zhenjiang.xu@gmail.com> writes:

> Thanks, Bastien. It's the default value - I've not changed it:
>
> org-file-apps is a variable defined in `org.el'.
> Its value is ((auto-mode . emacs)
>  ("\\.mm\\'" . default)
>  ("\\.x?html?\\'" . default)
>  ("\\.pdf\\'" . default))

So you need to check the relevant variable:

org-file-apps-defaults-gnu
org-file-apps-defaults-macosx
org-file-apps-defaults-windowsnt

If the relevant variable uses the defaults (as I guess),
you need to configure the mailcap file for your system

See http://en.wikipedia.org/wiki/Mailcap

HTH,

--
 Bastien