Is there a bus that goes to the Ming Tombs from subway line 15, Shunyi?

Well, there is no direct bus or subway that can take you to the scenic area.
According to your demands, you can take bus no. 945 at Shunyi Hospital, get off at Shahe North Bridge Station. Then transfer to bus no.878 to Dagongmen Station. After that, walk northeast around 280 yards to arrive at destination.