Well, from the end of Oct to Nov is the best time to enjoy the red maple leaves at the Fragrant Hill of Beijing. You could find the hill's introduction on this website's Beijing attraction.

thank you so much

one more follow up question..
can i go to mutianyu great wall and then go to ming tomb.. ? i know the most common route is ming tomb and then badaling great wall.. but i prefer the mutianyu great wall..is this possible?
and do youknow where we can rent a car.? we are 8 adults and 1 baby all in all

Hi Ms. lj, Mutianyu is further from downtown Beijing, and if you would like to visit it and the Ming Tomb in one day, you have to hire a van. Since you have 8 together, why don't you ask a travel agency to organize a one-day trip for your family only? This is much reliable and convenient than hire a van.