How long by bus from Hong Kong to Jiangmen?

Considering the time of passing the port, it will take you for about 3 hours to get to Jiangmen.
It is much faster by ferry to get to Jiangmen from Hong Kong, which will take you about 1 hour to reach Jiangmen. You can take the ferry at China Ferry Terminal at Central Hong Kong.

Rod, I just took this Ferry last week, from Kowloon HK to Jiangmen is about 3:15 NOT 1 hour. It is $HK 210 for the first class seat which gets you up top in a smaller area and they hold the lower class people until you disembark so you get to customs faster. I have also taken the bus to Jiangmen, but it was very much delayed for some reason where as the ferry was right on time.