How can I setup Apple pay in my iPad mini ?

You don't need any additional apps, as long as you are in the US with a US iTunes account, and have a supported credit/debit card (and are using a passcode on your iPad), then you should be able to set it up via Settings > Passbook & Apple Pay : Set up and use Apple Pay.

Ibrahem_1 wrote:

IIs there any any application to setup apple pay .

Do you have the iPad Mini 3? That's the only one that supports Apple Pay at this time.