Or did you want to say: He was brought up by his grandparents

Without more context, there are several correct answers. He will be brought up by his grandparents. He is being brought up by his grandparents. He has been brought up by his grandparents. ... and so on

Bring up is a phrasal verb that means to raise a child or care for a child until the child becomes an adult. In the active form, the grandparents bring up the child. In the passive form, the child is brought up by the grandparents. He is being brought up by his grandparents. He was brought up by his grandparents.

his grandparents are brought up or his grandparents are brought up by him