* Episode 18: "The Promised Day": He's introduced as a young prince from Xingese Empire, arriving in Central to learn about alchemy.
* Episode 20: "The Gate of Truth": He meets with Scar and witnesses his power.
* Episode 21: "The Homunculus of Greed": He encounters Greed and his minions.
* Episode 24: "The Alchemist of the East": He uses his knowledge of alchemy to help fight against the homunculi.
* Episode 25: "Alchemist of the East 2": He's captured by the homunculi and used as a bargaining chip.
* Episode 26: "The Homunculus of Wrath": He's freed by Alphonse and joins the fight against Father.
* Episode 48: "The Promised Day": He's instrumental in the final battle against Father.
* Episode 54: "The Final Countdown": He's shown mourning the loss of his father, the Emperor.
* Episode 63: "The Truth": He says goodbye to the Elric brothers and heads back to Xing.
Ling Yao is a recurring character throughout the second half of Fullmetal Alchemist: Brotherhood, appearing in many episodes.
These are just the main appearances, and he has other smaller appearances in the series.