Can we change airport on transit Visa?

Anchal, so you will fly from India to HK via mainland China? If so, as long as your layover in mainland is not more than 24 hours, you are eligible for the 24-hour direct transit policy and no entry permit is needed. You can change airports. If not, you should apply for a G type entry permit in advance. In this way, you can still transfer from one airport to another.