Almost anything stamped norinco will be non-corrosive.
There's some surplus Chinese ammo on the market that's corrosive, but it's not manufactured by norinco
https://www.canadaammo.com/product/detail/norinco-copper-washed-7-62x39-ammunition-crate-of-1200/ this stuff is corrosive, but norinco didn't exist until the 80s, box or packages will not be norinco
http://www.leverarms.com/chinese-military-surplus-7-62x39-fmj-non-corrosive.html they claim this stuff is non corrosive but several folks who've bought it are quite certain it's corrosive. You also won't find norinco stamped on it.
Canada ammo had two lots of non-corrosive 7.62x39 a while back, one lot was in wooden crates but civilian stale packages inside, and one lot in military packaging. All also marked norinco and quite definitely not corrosive. (The latter was also stamped "property of the department of the interior UAE" I've got a spam can of it left, i thought the markings alone were pretty neat)
All the other norinco stuff floating around, 7.62x51, .45, 9mm, 5.56, should be non-corrosive.