How do i get from Summer Palace to Badaling Wall if go by bus or subway and what will taxi cost?

Take metro line 4 from Beigongmen to Xizhimen and line 2 to Jishuitan Station, Exit B1.
Then walk east around 650 meters to get to Deshengmen Bus Stop. After arriving, take bus no.877 directly. The drop-off site is close to the pulley car lower station and about 10 minutes' walk to the entrance.
If you wanna take a taxi from Summer Palace directly, it would cost around CNY 250 for the single trip.