In mainpage.aspx having radcombobox and TabStrip, radmutipage and radpageview.
In radpageview content url page (page1.aspx) how to get the mainpage.aspx radcombobox. And if radcombobox onselecteditemchanged event i need to refresh the selected tab content url page(page1.aspx).
with reference to this form thread it is not possible to access the mainpage.aspx RadComboBox in the Page1.aspx. There is no relation between the mainpage.aspx and pages in the ContentUrl. As for your second question the Page1.aspx will get refresh whenever a postback happens. Please take a look into the sample code snippet.