The most significant Chinese inventions are referred to as the four great inventions 四大發明.
Si is four, da means big and fa ming means invention.
So what are these 四大發明?
造紙術 papermaking, it is generally accepted that papermaking was invented by an official during the Eastern Han dynasty. Before this, court documents were written down on bamboo slats. Despite the official story there is some archeological evidence of papermaking earlier in Chinese civilization, some think the Eastern Han simply perfected the art.
指南針 The Compass, in Chinese the compass is referred to as the point south needle (the needle which points south). You can see in this model of a Han dynasty compass that it was shaped more like a spoon, with a handle that would point south. Hence the name 指南針.
火藥 gunpowder, the chinese word for gunpowder literally means fire medicine, although technically the word yao has a broader meaning than just medicine. Nong yao or agricultural medicine is fertilizer for example.
The earliest records of gunpowder are from the Song Dynasty 宋朝, although the Chinese invented it and did use it in war, in various types of bombs and fire weapons, they did not figure out how to make the kind of advanced and devastating guns that appeared in the west centuries later. There were of course peaceful uses for gunpowder too, namely fireworks.
印刷術 The art of printing. The Chinese invented woodblock printing over one thousand years ago, and the first known book to use the method was the Diamond Sutra, a Buddhist text, printed in 868 AD. The method of woodblock printing was particularly suited to Chinese characters, the wood blocks would be carved for each page of a book and stored for when new versions of the book were needed. But they took a lot of space to store.
In the Northern Song Dynasty they invented movable type printing, which comprised a template where smaller blocks for individual characters could be added in to make up a full page of a book. This was more flexible because the characters could be re-arranged to make up different texts.