i am student in Malaysia and i am from Iran, i must go to Hong Kong for interview, do I have to get Hong Kong visa from embassy of China?

Yes, you have to apply for Hong Kong visa through China embassy in KL or China Consulate in Kuching to take the interview in Hong Kong.

Thanks for your answer , if my agent send my fill to embassy of Canada in Hong Kong , i have not problem for get a china visa? because i must will go to there for interview and this is important for me that, that time will be in Hong Kong if i lost interview i lost future, so that is very important for me that i get visa of china. thank you

sahimeh, I'm totally confused by your statement "if my agent send my fill to embassy of Canada in Hong Kong , i have not problem for get a china visa?"

You go to Hong Kong for interview, so you need a Hong Kong Visa. Why do you send your file to embassy of Canada in Hong Kong? Why do you want to get a China visa?