1. Fill up the I-139 affidavit of support. This form has to be endorsed by a Notary.
2. You need to have atleast 10k in your bank and take a balance statement
from your bank.
3. A letter addressed to US Consulate that you are inviting your parents
to visit you and that
you shall support all their expenses during their
stay.
4. A letter from you to your parents inviting them to stay with you
5. Copy of your passport (all the pages) and H-1 papers.
6. A letter from employer stating that you are employed and what salary
you draw.