Package CJK Error: Invalid character code about hnuthesistemplate

[leaf-hsiao]

Did you save your reference.bib with UTF-8 encoding?

[Qinghev]

how to save reference.bib with UTF-8 encoding?

I opened it through notepad, then added some contents and saved them.
I ran latex-->bibtex-->latex. While the contents were English, it worked well.
The error showed up after I inserted Chinese items.

I opened reference.bbl through notepad, the content was right.
If I ignore the problem, then all the Chinese items are unintelligible text.

[leaf-hsiao]

Notepad add a BOM in your file. Use Notepad++, VSCode or other editors instead.

[Qinghev]

How to add a BOM?
I use Ctex to create a new bib document, still not working.

[Qinghev]

Problem sovled.
reference.bib was saved with ANSI encoding, I save the document as ... , then I could change the encoding method to UTF-8.
Thank you.