We'll take train from Paris to Madrid then catch flight at airport. We only have 2 hour to do this. Anyone can tell how far from train station to Airport and what is fast way get to airport. Great appreciate for any comments.

Well, if you dont' mind spending the money, take a taxi. There are dozens of taxis waiting outside the train station in Madrid.

I took a taxi from there to the airport and I think it was about 2000 pesetas. (more or less)It didn't take more than 20 minute either.
Good luck.

From Chamartin train station to the airport with baggage, it cost me 2600 pesetas in September via taxi. Trip took about 25 minutes do to very light traffic at 6am.