Best way to get from Shanghai to Putian? Is there a fast train?

It's suggested to take direct high-speed train from Shanghai Hongqiao Railway Station. The trains depart from 06:40 to 14:45. It takes around 5.5 to 7.5 hours on the way. The ticket fare of second class seat is CNY408.5 and first class seat is CNY666.5. :)

Do we need to pre-buy tickets? How do we get on a 5.5 hour one?

To guarantee a ticket, you are advised to buy the ticket in advance. You can search for the train details on this website to see which train has the duration of 5.5 hours, then go to railway station to buy that train or book directly on this website to save you trouble.