Mains electricity in China is 220 V. If you are travelling from a country that uses 110 V mains supply (e.g. Japan, North America), you may need a converter for electrical devices (e.g. hairdryer, electric shaver).
There are two types of wall socket in China (see photo). Some wall points only have one of the two socket types. The two-pin socket at top can take plugs with two flat pins (Type A, as long as the two pins are the same size), or two round pins (Type C/E/F). German standard plugs should fit these. The three-pin socket at bottom takes Type I pins (same as Australia and New Zealand).
You may also find extension packs with universal sockets, which can take UK and other types of plug.
If in doubt, bring a universal adapter plug with you. These can also be bought in China.