any problem for old person to walk or climb huanglong and jiuzhaigou?

The cable car is available in Huanglong. Considering your parent's age, he can go up to the top area by cable car in Huanglong and go down on foot. The sight-seeing buses are also available in the Jiuzhaigou valley. The bus can transfer your parent from a spot to another. It's convenient. The only thing you should bear in mind is the altitude sickness. But you needn't worry about it. The oxygen bottle can be bought there. If your parent is afraid of altitude sickness. It's better for him/her to take some medicine in advance.