Simatai is closed for renovation.
From Beijng to Jinshanling, take bus no.980 at Dongzhimen Long-distance bus station, get off at Miyun bus station and then hire a car(rmb100-200) to Jinshanling. You can also share a car with others to save money.

If you are in Beijing and go to Tianannam Square there are some travel agents around square who offer trips to Simatai about £20-£30 each.

They picked us up Hotel but beware mini buses may be used not coaches be sure mode of transport but worth it when you get there

Anyone know when Simatai will reopen?

No official news about the opening time by now, Mr. Lightner. If you come recently, change another place, for example Jinshanling Great Wall.