回複：為父母申請移民的準備材料

I-130 is required: your birth certificate, your us passport, the paper that can show the relationship between you and your parents. After the INS approved your I-130, then your case is going to transfer to the NVC(National visa center)...
After the NVC approved your case, then it will be transfer to Guong Zhou. ----interview time----get visa---green card.

Hopefully, it helps!
Michell