There are two “Golden Weeks” in China. The first one, also called Spring Festival or Chinese New Year, is celebrated in either January or February depending on the Chinese Lunar Calendar. The second Golden Week takes place in early October, where founding the People’s Republic of China is being commemorated. To be able to have a full week off, Chinese working people will be on duty on September 28th (Saturday) and October 12th (Saturday) to add some extra days to the 3 days legal holiday and make it one whole week of national holiday (October 1-7).
If you consider exploring China, try to avoid this week. Last year 726 million Chinese were travelling domestically (7 million abroad) to either visit their families or go on holiday during this week. Flights are expensive and train tickets, available 60 day prior to departure, are sold out in minutes.