Police arrested 251 men and 66 women aged 15 to 77 in an anti-triad blitz from March 21 to April 20.
Officers raided more than 150 locations across the city.
The arrests were for offences including claiming to be a member of a triad society, criminal intimidation, blackmail, wounding and drug trafficking.
Police seized choppers and machetes, gambling paraphernalia, drugs worth more than $200,000, pornographic discs worth $6.7 million, and cash.