What system controls the endocrine system

The hypothalamus and pituitary gland controls the endocrine system. Endocrine system has to do with a lot of hormones. The hypothalamus kicks in telling the pituitary gland (also in the brain) that it needs to let out hormones.

it's the part of the brain that controls the endocrine system?

Explanation:

The pituitary gland, which hangs by a thin stalk from the hypothalamus, is called the master gland of the body because it regulates the activity of the endocrine glands.