I can't see it in the Chinese Civil War, but let MacArthur and LeMay at it during Korea and Manchuria becomes a smoking irradiated ruin. Nine weapons were made available should they be needed; MacArthur wanted thirty to fifty. Either is probably enough to win the Korean War, but conventionalises nuclear weapons. They'll probably be released for VULTURE in 1953, for instance; probably not Suez, but I wouldn't bet on it. There won't be a Vietnam War, and probably no Cuban Missile Crisis.
I suspect that Stalin turns to Truman and says 'hey, wasn't us - that Mao was a loose cannon, we're glad you dealt with him'. Or something like that, rather than going to a general war. And a nice symbolic purge of any surviving 'volunteers'. The Soviets are unlikely to take Western Europe, but the demonstrated willingness to use nuclear weapons won't affect them too much. They planned on it themselves, and assumed we'd do the same.
In fact, it probably means the Nth-country problem becomes a bigger one - since nuclear weapons are a real, usable weapon rather than a symbolic capability, they're much more desirable. The Swedish bomb won't be cancelled, Canada's latent capability will be realised, Western European powers will get their own bombs, Australia will be strip-mining the Outback to keep up with demand for uranium. By the time a non-proliferation treaty is on the table, it's too late - the world is already mildly radioactive.
The consequences of ripping the industrial heart out of China, I can't be too specific on. But I think we can assume 'lots of casualties, economy ruined' as a starting point. It may well rekindle the Civil War. It certainly won't be pretty.
On the other hand, since going to war with any power worthy of the name means getting nuked, it doesn't happen very often. The result is a kind of uneasy peace, which could flare up into global thermonuclear war easily. That threat probably means there's lots of ABM - even if you're vulnerable to a massive attack from a superpower, it gives thinking time against light attacks and reduces the risk of escalation.