Sorry, I missed a one question
Can I convert text to Chinese?
If can, which php file can to change?
@hidychow
For extensive changes like that, I recommend finding a local developer who is comfortable with PHP, WordPress and WooCommerce extensions. They can then ask us for support directly on the GitHub page for this project (at https://github.com/star-micronics/star-cloudprnt-for-woocommerce).
Chinese printing should work already as long as you have a suitable printer model (mC-Print series recommended, TSP650II can work also but may need some additional configuration) and have selected UTF-8 based printing from the settings page.
Version 2.1 of this plugin will be fully translatable, via the standard methods of providing translations for WordPress plugins. The current 2.1 branch on GitHub is not feature complete, but fully supports translations, so your developer can take the project from there and help you translate it (both the user interface and receipt data).
Alternatively, if you want to translate the built-in strings in the current official version of the plugin, then you should find them all in the file order-handler.php. Be warned that there may be some column alignment issues when using full-width characters with the current version of the plugin, again this has been resolved in the 2.1 branch.