i dont know why my website show in google like this , mydomain.com !?
not WWW.mydomain.com also all other pages of my website shown without WWW !? while all other websites shown WWW.domain.com in search result ?
can anyone tell me why ?
You need to do proper url structuring, remove these !? signs. It will improve your website ranking. Best SEO practice is to have page naming convention to make best use of keywords or keyword phrases. I think one of the most important requirements is URL structure and page naming. What I am referring to is setting up the website structure.
TechnoBear has given you the solution, but what it comes down to is what version of the URL most of the links point to, including those on your own site.
But does it matter? As long as the pages are listed and indexed consistently, you'll get the same results whether they are using the www version or not.
If you specify your preferred domain as http://www.mysite.com and Google finds a link to your site that is formatted as http://mysite.com, Google will treat that link as if it was http://www.mysite.com
But, I whole-heartedly agree with Stevie D when he says: TechnoBear has given you the solution
Yep, use Google Webmaster Tool is the best way to fix your problem. You also can make a 301 redirect, but it might be a little risky if you have added lots of contents to your website.