Restaurant up by the main entrance to Mùtiányù Great Wall. It does OK Chinese food.
Just up from the west car park, between a KFC and a Subway, try Yong He King for the Chinese version of fast food: rice meals, dumplings, noodles.
Just up from the east car park at Bādálǐng, this place does OK dumplings, as well as rice and noodle dishes. It has a picture menu, so you can point and pick.
One of the few restaurants by the west gate of Jīnshānlǐng Great Wall that stays open in winter. It has an English menu.