Beijing imposed the security law on Hong Kong last week targeting acts of subversion, secession, terrorism and foreign collusion with a maximum penalty of life imprisonment, in response to huge and often violent democracy protests that erupted past year.
Organizers said 582,000 people had voted, in the city of 7.5 million, at the end of two full days of polling-more than expected, and representing around a third of voters who backed the democrats in an election previous year.
Organisers said 500,000 people had voted by late afternoon on Sunday, in the city of 7.5 million.
Benny Tai, co-founder of the 2014 Occupy Central movement, and one of the organizers of the Democratic primaries, said today that democratic groups could get more than 45 seats in the new Legco (the local Parliament), gaining a solid majority.
"A high turnout will send a very strong signal to the global community, that we Hong Kongers never give up", said Sunny Cheung, 24, one of a batch of aspiring young pro-democracy advocate out lobbying and giving stump speeches.
Pro-democracy campaigners in Hong Kong say primaries to choose candidates for the upcoming legislature election have drawn far more voters than expected.
Last Friday, Hong Kong police raided the office of the independent pollster helping with the election, and officers copied some information from computers there.
However, the police raid may have helped publicize the primary election, with news of the event circulating throughout the city.
Hong Kong's sovereignty was handed back to China by Britain in 1997 and certain rights were supposed to be guaranteed for at least 50 years under the "one country, two systems" agreement. "But I'm not afraid of any "white terror" since I'm only exercising my rights".
Almost half of respondents said the possibility of extradition to the mainland for a trial - which the new security legislation allows - was a "game changer" for Hong Kong's position as a trusted global financial center. Libraries and schools have pulled books, political parties have disbanded and one prominent opposition politician has fled. Online, people cleaned up social media profiles and deleted accounts, and asked contacts to delete WhatsApp messages from them.
The law, which gives the Chinese state new powers over the city, drew widespread worldwide condemnation.
Last week, Australia joined Canada to suspend its extradition treaty with Hong Kong.
Significant uncertainty stays around the regulation, and many teams inside the town not specifically focused by it - NGOs, media companies, and corporations - are waiting around to see how it could have an effect on them.
Authorities say that slogan now contravenes the new security law.
"The uncertainty of the laws is a little bit worrying and the latest conflict amongst USA and China", 1 respondent was quoted as indicating.