I am a Tajikistan, Where in China should I apply for visa to HK?

You can submit your visa application to the Immigration Division of the Beijing Office of the Government of the HKSAR in Beijing.
No.71, Di'anmen Xidajie,
Xicheng District,
Beijing, China
Postal Code 100009
Tel: (8610) 6657 2880
Fax (8610) 6657 2821
E-mail address: bjo-hksarg.org.cn|bjohksar

Or send application directly to HK Immigration Department.