Any economy that saves 45 percent of GDP will tend to run a current account surplus, China included. Keeping its current account surplus down takes extraordinary (though largely off-budget) fiscal effort. And faster financial account liberalization almost certainly would result in a depreciation and push China back toward surplus.
China's surplus is down relative to its pre-global crisis level, both in dollar terms and as a percent of China's own GDP. The same cannot be said of China's neighbors. East and Southeast Asia are still a substantial exporters of savings to the rest of the world.
A deep dive into the details of China's balance of payments over the last few quarters of data. During the dollar's depreciation in 2017 and the first quarter of 2018, it looks like China was adding to its official assets once again—though the growth largely came from the state banks.