#utf-8

I tried so many ways to kill this problem.
I use wkhtmltopdf to product pdf with chinese characters(中文字符)

at last


...

This add to entity-print--webform-submission--notes.html.twig all is ok.

BUT IT'S IMPORTANT: if you use wkhtmltopdf,you must download font SimSun and set as first font like this
body {
font-family: "SimSun","Microsoft YaHei", Helvetica, Arial, sans-serif;
}