Transit Visa for Cambodian Passport holder

First, prepare the relevant documents: travel itinerary, copy of passport, the application form, a passport-style photo, financial support proof, flight tickets and hotel booking record.
Next, submit the application to China embassy or post it to HK immigration department directly.
Address: Receipt and Despatch Sub-unit
HK Immigration Department
2/F, Immigration Tower
7 Gloucester Road
Wan Chai, HK

Thank for your detail information.
I viewed the required application forms and the sponsor application is also needed, according to my first time taking a transit at HK, I'm afraid, I can't complete that, because I know no one there.
Could you please verify more, if I only submit my application without the sponsor application, is it possible for me to get the transit visa?

As I know, sometimes in real practice, the consular officers may require a sponsor. But sometimes the sponsor is not necessary. You can have a try! But I cannot guarantee the result. If you still doubt, you can contact with the HK immigration department to Inquire. TEL: (852) 2824 6111