If you just want practice, I have a different idea. Look at the English Wikipedia, en.wikipedia.org. Look for topics about places in China or aspects of Chinese history or culture that you understand well, that do not have articles, or have only short or sketchy articles. Learn the techniques, which should be easy for a software engineer, for editing WIkipedia. Anyone can do it. It is best to set up an account which you can do in five minutes and costs nothing, but you do not even need to set up an account. It is important to understand Wikipedia's rules, of which the most important is that you need to cite a source for every fact. Your English should be good enough to understand, but you will be amazed to find that other editors will be quite happy to correct your spelling and language mistakes.

Thank you for you advice. I will think about that. :)

I think it's a good idea,but I don't think that writing a children's novel is easier than writing an adult one.If you choose that because you love to write and you want to write for kids then it's fine.But don't choose to write a children's novel just because you believe it is easier.That's my opinion anyway.