Big bone, also called soup bone, is more suitable for making soup. If the bone has cracked, don't blanch it. If not, you can blanch it first. Boil the cracked bone directly in water, and remember to skim off the foam so that the bone marrow will not be lost. Bone soup must be stewed for more than 2 hours. Boil with high fire and simmer with low fire, and 2-4 hours is the most suitable. Stewed soup can be cooked with yam or other ingredients.