HI, I use timer control in my page.

each 10 second i show one of some pics in my page by timer control.

problem is here, when i am scrolling in my page, when pic change, page scroll to top of page (my images change in top of page).

any one has Idea about it? 

Don't use the UpdatePanel for this... I recommend using the SlideShow control in the AJAX Control Toolkit.  The result is much nicer and is much less overhead than the UpdatePanel and Timer. 

-Damien