I need to get some family to barca airport from salou on 28 december are there any buses from salou ,thanks.

This is the timetable for Plana buses to Barcelona Airport over the winter. You'll need Adobe Acrobat Reader to view it.

http://www.itenewebs.com/autocaresplana/Documento.asp?w=1&idc=1978&tipo=HORARIOS

if the link doesn't work then start here.

http://www.autocarsplana.com/

Hope that helps.