If the subtitle you find is slightly out of sync, most media players (like VLC or MPC-HC) allow you to adjust the timing manually using shortcut keys (usually and 'H' in VLC) while the movie is playing.
If you prefer not to manage separate files, you can watch The Mermaid with built-in English subtitles on these official platforms: subtitle The.Mermaid.2016.CHINESE.1080p.BluRay....
: A highly-rated site for verified movie subtitles. If the subtitle you find is slightly out