It is unclear if your ex took a voluntary departure or he was deported. If the latter, he cannot come back for at least 5 years unless he has permission from the USCIS to reapply for admission early. If he took voluntary departure, he may come back provided he can get a visa. Your six year old child cannot petition for him as children must be 21 to petition for parents. Consult with immigration lawyer for advise.
Answered on Aug 24th, 2011 at 7:35 PM