Question: how to train your dog not to bite leash?
Answer: Step 1: Introduce an acceptable tug toy. You don't need or want to get rid of the tugging behavior completely. ... 
Step 2: Start training and rewarding good leash behavior in your living room. In the living room? ... 
Step 3: Puppy on leash in the living room. ... 
Step 4: Reward with tug. ... 
Step 5: Take it to the streets.