I have immigrated to Canada, and my brother is mentally retarded. Can he apply for family reunion and immigrate to Canada?

It depends on your brother's level. We have encountered similar applications before, so we looked up a lot of information.

If his degree is serious, such as he can't take care of himself in basic life and needs long-term special care, he will not meet the requirements of immigration application, because it will cause a serious burden on social services in Canada. The following is the original text of the Immigration Bureau:

The application for permanent residence will not be accepted if the person's health condition:

Pose a threat to public health or safety; or

Will cause excessive demand for health or social services in Canada.

Your brother's situation belongs to the latter situation.

So unless you can prove that your brother will not be a burden to Canada, one of the options is that you can arrange a large sum of money and tell the Immigration Bureau that the money is specially prepared for your brother.

I hope I can answer your question.