Transfer airport to hotel grand mercure beijing 7.4. airplane arriving 7.15pm

Oh, you must refer to Grand Mercure Xidan BJ, right?
If yes, take airport shuttle bus line 2, and get off at Xidan Station. The operating hours are from 07:00 to 24:00. It costs CNY 24 per adult. It takes around an hour on the way.
After arriving, walk to the west along West Chang'an Road. Then walk to the south along Xuannei Avenue to your hotel. The total walking distance is about 0.5 miles.