Three minutes. According to Baidu map, the China-Hong Kong subway station is 880m from Hong Kong Station to Central Station, and it takes 3 minutes to walk. The walking route is as follows:

1. First enter Gangjing Street from Hong Kong Station of China Metro, drive 170 meters, turn left, enter Connaught Road Central, and drive for 370 meters.

2. Next, turn left, enter Du Street, then drive 60 meters, turn left again, enter Des Voeux Road Central, and drive 140 meters.

3. Finally turn left into Chater Road and drive140m to reach the destination.