Police said officers found about 59kg of suspected cannabis flowers, estimated to be worth HK$12.3 million, in a car boot in Tin Shui Wai.
Officers searched a flat on Tin Yan Road, found a car key and then searched a car parked in the estate car park, police said.
Two local men, aged 40 and 67, were arrested on suspicion of trafficking in dangerous drugs. The two were reported to be father and son. The 40-year-old was provisionally charged with one count of trafficking in dangerous drugs.
The 67-year-old was released on bail pending investigation. The 40-year-old is due to make his appearance at Tuen Mun Magistrates' Courts on the morning of 26 October.