Different from regions.China is a really Large country. Climates are so different from north to south, or west to east.
But i recommend you can travel to the south regions in winter, which are not colder than north regions. And in summer and autumn, you can go north regions, such as Beijing and Xi'an, besides, Beijing's autumn is very beautiful.
Regions with beaches in China are also good places to go, you can go there any time available.