Shuttle trains from Pisa Airport and Pisa Central Station

Every day a shuttle train links Pisa Airport Station to Pisa Central Station in 5 minutes.
Departures from Pisa Airport Station between 6.53 a.m. and 9.03 p.m.
Departures from Pisa Central Station between 6.38 a.m. and 10.02 p.m.

See timetable 

Pisa Airport Station is just inside the Airport check-in area; departures and arrivals from Pisa Central Station at platform 14.
Only second class service. Price 1,10 Euro

Tickets can be bought on this site, at Trenitalia Ticket offices; Selected Travel Agents and Ticket Vending Machines both in Pisa Airport and Pisa Central station.

Fast Regional trains from Pisa Airport and Firenze SMN (Main station)

A Fast Regional Train Service links Pisa Airport and Firenze SMN (Main Station).
Only Stopping at Pisa Central Station

PISA AIRPORT - FIRENZE SMN

Train	Dep	Arr
3138	9.03	10.00
*3150	11.03	12.00
3154	13.03	14.00
3156	15.03	16.00
3170	17.03	18.00
3178	19.03	20.00

FIRENZE SMN - PISA AIRPORT

Train	Dep	Arr
3139	7.00	8.00
3151	11.00	12.00
*3163	13.00	14.00
3167	15.00	16.00
*3177	17.00	18.00
3179	19.00	19.49

* From Monday to Saturday

First Class Ticket: 8,70 euro   Second Class Ticket: 5,80 euro
Tickets can be bought on this site, at Trenitalia Ticket offices; Selected Travel Agents and Ticket Vending Machines both in Pisa Airport and Firenze SMN.