Valve is going to introduce an official Chinese version of Steam. For this, the company has partnered with Perfect World, the Shanghai company that has been working with Valve for years to distribute the Chinese versions of Dota 2 and Counter-Strike: Global Offensive.
The name Steam China is officially registered in China, but Valve and Perfect World have not yet announced a release date for the Chinese version of Steam. Valve has also said nothing about the impact of Chinese rules and censorship on the offering of the Chinese version of the game service. For the non-Chinese Steam version, which can be accessed elsewhere in the world, nothing changes.
Steam is in principle accessible in China, but that is unofficially. Parts of the game service were blocked in China at the end of 2017 and Valve probably wants to prevent this kind of blockage by entering into a partnership with a Chinese company. It can also better target the large Chinese market with Steam China.
Perfect World is a major Chinese game and film company that has been working with Valve since 2012. In that year, the Chinese company obtained the licenses to distribute Dota 2 and later Counter-Strike: Global Offensive, two major esports titles in China. The CEO of Perfect World says his company will introduce even more games through Steam China.