This lovely snake is the Red Mountain Racer.
aka The orange slope crawler, as that is a much more suitable name.
for more information about this wonderful snake and many more, see www.hongkongsnakeid.com. www.hongkongsnakeid.com . for example this on its HABITAT
Now very rare in Hong Kong the Red Mountain Racer is known to inhabit high elevations sometimes exceeding 800m and seems to prefer cooler temperatures with many sightings occurring in the winter months. Can be found on grassy and rocky mountain bluffs as well as high elevation forest and bamboo groves. The authors have also found one specimen, a mature gravid female, just above sea level actively moving at night.