How to do merit to make parents healthy?

In addition to chanting the holy names of buddhas and bodhisattvas, chanting scriptures and reading books.

You can also release them, give them to your parents, and return their merits to them.

In addition, you can recite the Wishing Sutra of the Tibetan Bodhisattva for them.

As long as you are diligent in learning Buddhism, doing good deeds and giving whatever you want, acting according to what the Buddha said, and repaying your parents devoutly, they will all benefit.