Is it better exercise to walk on grass or pavement?

Walking on grass will be better than walking on pavement.  The impact from walking is minimal so you should be able to walk on both surfaces with minimal stress on your body.  However, walking on grass will give you the extra cushion that may benefit your body, especially if you have knee, hip, or back pain.  On the reverse, many people do not have access to grassy route and walking on pavement might be more convenient.  Again, either surface will be light impact on your body so I recommend choosing what is most convenient to keep you active!