Is there any boat service from Beijing Exhibition Centre to Summer Palace in late December?

Yes! You can take a boat to the palace from Huangdichuan Wharf at the rear lake of BJ Exhibition Center. The boats are available from 10:00 to 16:00 at hourly intervals. The trip takes about 1 hour. The fare is CNY 40 for a single trip; CNY 80 for a round trip. Just buy the ticket on the spot upon arrival! :)