Any kind of equipment relating to defense?
assuming that you are talking about mainland china, not taiwan.
they are under an arms embargo right now. so sales of weapon systems would be illegal.
but it is much murkier on sales of technology, especially dual-use technology.
before the embargo was put in place, china was a buyer of western weapons. I think they have a fleet of black hawk helicopters.
edit: I forgot to mention that western countries sold many diesel and gas turbine engines currently used on chinese naval vessels. China also developed its horwitzers, both ultra-light weight and self-propelled, with help from some western countries.
Besides that as far as I know most of the European nations and the US to not have arms deals with China for strategic/political reasons.
The US military buys parts from China. As recent as 2014 Obama prevented a law passing that would block purchase of China products: (thenewamerican.com - Obama Pentagon waived ban on chinese parts in US weapons). You and I have a household budget and buy made in China stuff from Walmart to save money. The Pentagon also has a budget (a little larger at $600B+) and will buy stuff from China too. Somethings may not even be made in America anymore.
I can see Trump trying to change that after someone tells him. For example find out the most popular computer chips bought from China and setup plants in America to manufacture them. Then coerce Canada and other major trading parties to buy American rather than Chinese, possibly with export subsidies.