Who are key CCTV manufacturers in main land China.

Sihai Electronics Co, Ltd
http://www.sihaielectronics.com

Bestintro Information Technology co.,Ltd
http://www.net158.com 

ZHUHAI EVERPO CO.,LTD
http://www.everprocam.com

Hope this helps!

Regards,

Pinkslip

If you're looking for key manufacturers in terms of market share, I
think this information is hard to find because it isn't usually
covered by syndicated research (though you may have some luck with
China Yearbooks).

However, I know offhand of Nanwang Multimedia
(http://www.nanwang.com/english/)  as a large video
surveillance/conference systems manufacturer and Zhongliandun
Industrial (http://www.zhongl-dun.com/en/).

If you want a broad listing of "premium suppliers", you could search
for CCTV Camera suppliers under the "Gold Suppliers" community on
Alibaba.com (the largest online sourcing marketplace). Gold suppliers
have to pass some kind of authentication process via a third-party
credit agency and pay a US$5000 annual fee. Through the directory, you
can see a profile of each supplier (and even a video tour in some
cases).

Here you go:
http://chinasuppliers.alibaba.com/search/china_products/CCTV_Camera.html