Yes, walking is helpful. Exercise is a key component in treating PAD. Actually, the success of treating PAD is measured by how far you can walk without pain. Walking helps your muscle condition.
However, an exercise plan should be appropriate. Always begin slowly. Walking outdoors, or on a treadmill are both okay.
Listen to your body. When you feel pain, you pause, wait for the pain to fade, and begin again.
Stretch before and after you walk.
Slowly but don't give up.