someone backed up my iphone, using his laptop. he did it with the purpose of transfering all my data on my new iphone. is it possible that he can access my data:photos, messages,etc, from his laptop now?

If he has his own iOS device, yes, he could just restore that backup to his device and he'd have a mirror of your device to use. Unless this was an encrypted iTunes backup, it will not contain any of your passwords, health or other sensitive personal data in it. But it will have whatever was in your camera roll at the time, your iMessage and SMS texts, notes in any local notes app storage, etc.

There are also windows and OS X tools to parse and see the data in an unencrypted iTunes backup file. Why did you ever allow this person to do this if you do not trust them or did not have control over the process to delete the backup once done?