How long is the journey from Beijing airport to Ba Da Ling.

Annie, it is very expensive if you catch a taxi from the airport to the wall. A single trip costs around CNY 250. However, the taxi driver may not wait until you finish climbing the wall. So I don't think taking a taxi is a good idea.

You may take a taxi from the airport to Deshengmen. It takes around 70 to 80 minutes and costs around CNY 80 to 90. There you can take no.877 bus to Badaling. It also takes around 70 minutes from Deshengmen to the wall. Please remember that the last 877 bus leaves at 12:00.

Or you can take airport express line from the airport to Dongzhimen, change subway line 2 and get off at Xizhimen Station, exit A1 and walk to Beijing North Railway Station. There you can take S2 train to Badaling. It's fast and just costs a few bucks.