There are 1.6 billons people in China, may be 99 percentage are not Muslims, so all those people will go to Hell? Oh my god!

Praise to be Allah, the lord of the World; and may His blessing and peace be upon our Prophet Muhammad and upon all his Family and Companions:

It is reported by Muslim (in Sahih) and others about a debate between the Paradise and the Hell-fire, Allah Almighty said: And both of you (Jannah and Jahannam) will be filled. And in the Qur'anic verse we read: {On the Day when We will say to Hell: "Are you filled?" It will say: "Are there any more (to come)?"} [50:30].
This Lord's Hadith which we mentioned is a clear evidence that the Fire expands for the disbelievers, and even as they reach a great number, the Hell-fire will ask for more. This is not unusual for the sensible person to believe, because Allah Almighty Created all creatures, He is their (our) sustainer and He is able to have mercy upon whom He wants and He can punish also whom He wants.
This is considering all creatures from the very beginning of this world to its end, so why you are surprised about China or some other country like it?
You should be more surprised that the percentage for the Hell-fire from Adam 's descendants is 999 from 1000 (99.9 percentage) and the percentage of the Paradise from them is one from 1000 (0.1 percentage). The Prophet Muhammad (Sallallahu Alaihi wa Sallam) said: "It will be said: O Adam! Take out (collect) the Fire's group from your descendants!" Adam will say: 'O my Lord! What is the Fire's group?' It will be said: 'From each 1000, 999. (It means that 999 human being will enter in the Hell (the Fire's group) and only one will go to the Paradise). And that is a day when the small child will become gray-haired and every pregnant female shall drop her load (unformed), you shall see mankind as in a drunken state, …" . [Reported by Imams Bukhari and Muslim ].
Allah knows best.