Could you tell me how to go to Hong Kong from Beihai?

In Beihai,you cannot find the cross-border buses from Beihai to HongKong. But you can transfer to Wuzhou in Guangxi or Nanhai in Foshan first and then take the cross-border bus there to go to Hong Kong.
In Wuzhou, you may take the bus at Jinhui Bus Station at 08:00. The bus reaches Jordan and Mong Kok.
In Nanhai, you can take the bus at Pingzhou Hotel. The buses leave the Pingzhou Hotel at 07:40, 08:40, 14:25 and 16:40.

by air. there is direct flight from beihai to hongkong