As everyone know,wow version is still 2.4.3 in china.
Today,i update my addons by curse,but some libs and addons give me a lot of error msg and not work,so i want to know how to update these addons to "Interface: 20400",not to "Interface: 30000" by curse?
You can't, at least, not by the curse client. You will need to go to Curse website and manually download older versions by hand one by one. Every addon should have a zip file list near the bottom of the page that lists all the zips and their older versions.