If you use VLC then you can select the subtitles in the open menu. But if the .sub file(s) have the same name as the movie you want to play, the player is probably reading the subs.
If the player is actually reading the subs but still you get no output of it, then it may be because the fonts to read that language are not available. But at least the subs are in chinese or some asian language that shouldn't be the case. If this is the case, then check your distro's site and find out how to install these fonts.
Hope this helps.