How to get to train station from Haikou airport?

Do you mean your arrival time is 11:10 am?
If yes, you can take airport shuttle bus to Xiakan Village. Then take bus no.37 to the railway station directly. The frequency of the shuttle bus is 30 mins.
You can take this frequency as a reference and buy your train tickets.

what train do you need? bullet train to sanya or HK east is in
the lower level of the domestic terminal.

if you want one of the very few trains going to the mainland, then
you take the bullet train to haiko station.