overnight train venice to sorrento?

Any chance you can extend your stay in Venice or start one day earlier in Sorrento? If not, you might want to do a one-nighter somewhere in between. Maybe Florence?

No such night train. Trenitalia does not serve Sorrento. The closest you can get to Sorrento on Trenitalia is Naples or Salerno. To get from Naples to Sorrento, you will be on the private Circumvesuviana train system. For the night train out of Venice, there is one departing from Venice Santa Lucia at 23:30 but you must change trains at 06:20 in Rome to get to Naples. There used to be a night train from Naples to Venice coming from southern Italy so I was looking for the reverse. I don't see either run anymore.

thanks, I did some research and actually booked a flight from venice to Naples, then we can take a shuttle to Sorrento, and get a day at Capri

The flight is a great solution. Hopefully, you will arrive early enough in the day to take advantage of the bus or ferry transportation from Naples Airport to Sorrento. If you arrive late in the evening, all major shuttles, ferries and even the Circumvesuviana train will not be operating. You will be left with private transportation only.