Is there a bus from Beijing Dongzhimen headed to Chengde?

Oh, as I know, there are some long-distance buses at Dongzhimen Bus Station that can take you to Chengde directly. But I cannot find the bus schedule. You can check is again before you start off. Or you can take long-distance bus at Sihui Bus Station. The schedules are from 06:30 to 19:00 with the ticket fare of CNY 85 per person.
After arriving at Chengde Bus Station, you can easily find a private car to get to Jinshaling Great Wall.

If you wanna go to Jinshanling Great Wall from downtown area directly, take the tourist bus near West Wangjing Metro Station (at the bus stop opposite the exit D of line 13 or exit C of line 15). This route only operates from April to November.
The bus schedule is at 08:00. And the return bus departs at 15:00.