After I change my baby formula to Nan 1 HA ~ he shit watery green color ~ is it normal?

the green color is because of iron in the formula. regarding the watery poo, you need to make smooth transition from the previous formula to the new one. mixed only 25% of the new formula with 75% pevious one for few days, than 50%, 75%, then 100%. baby's digestive system needs to make adaptation.