持香港特區護照到 柬埔寨 可落地簽証嗎?

No, you can get an On Arrival Visa in Cambodia. It is cheaper to do it in Cambodia ($20) and you will get a single entry visa for one month.

e-visa costs $25 ($5 is the processing fee) so I recommend you to get the On Arrival Visa.

Visitors arriving by air can obtain a visa for stays of up to 30 days on arrival at Phnom Penh International Airport, Phnom Penh or Siem Reap International Airport, Angkor. Visas are also available from Immigration at the border posts of Bavet, Poi Pet and Koh Kong. Visitors are advised to check current situation before travelling. E-Visas are only valid for entry via Phnom Penh International Airport, Phnom Penh or Siem Reap International Airport, Angkor.

But beware that the queue for the On Arrival Visa is very long. They work very slowly indeed. Then you need to queue up to clear immigration.

Check out the e-visa website.

I just saw there's an e-visa as well. Only 25USD. But you've to scan your passport photo and upload it on the e-visa website. And you'll be in a different queue for e-visa while your tour group in another queue I think. And visa at arrival normally would be a massive queue. (From my exp in Bali)