I want to set the newtab to a blank page,but I can not find the function in the settings.What's more,I want the function to hide the round button in the right top which is used to seach a tab page.
As with Chrome itself, you will need to use an extension/add-on to change the new tab behaviour.
In CCleaner Browser go to the Chrome webstore and find the extension you want, then click on 'Add to Chrome' which should add it to the CCleaner browser.
There are many extensions to choose from, (and many that do the same thing), eg. for a blank new tab pick from one of these:
https://chrome.google.com/webstore/search/blank new tab?_category=extensions
The search button is another question.
You used to be able to disable it with a 'flag' switch, but AFAIK google removed that switch so users are now stuck with that button.