what shoud I do for the driver, when CYUSB3014 as a host and connecte to usb mass storage device such as USB Flash Drive.
You've to write your own driver and run file system stack over it.
We've a Ez-Host based kit CY4640 which runs FAT file sytem on it. You should be able to use that as reference for the FAT file system part. For the other part you'll have to modify code to FX3 equivalents.