I want to go to zhongda in Guangzhou from Hong Kong tuen mun. Pls advise any direct bus.

As I know, there is no direct bus available. Then I would suggest you take a taxi to GZ Hotel. Near the hotel, cross-border buses are scheduled to HK and they leave at 07:15, 08:00, 09:30, 14:30, 16:30 and 20:30. It costs 100RMB per person. The buses mentioned above are operated by Trans-Island Limousine Service by the way.