See Weapons of OoT for an explanation of why you will be using Deku Sticks (two of them in total) for this battle.
Stand right in front of King Dodongo's mouth, whip out your first bomb when he opens his mouth and lob it in. Get out a Deku Stick and jump-attack him using Z-targeting. Stand aside while he does his roll attack; then repeat. Your second attack should kill him.
|Bosses in The Legend of Zelda: Ocarina of Time|
|Gohma | King Dodongo | Barinade | Phantom Ganon | Volvagia | Morpha | Bongo Bongo | Twinrova | Ganondorf | Ganon|