You can invite your parents to visit USA on B1/B2 visa category.
You will need some basic documents like: I-20, OPT card, your passport and visa copies, your financial documents (if any), Marriage certificate (if married).
Now the US Visa website is changed so I do not know where will you find the following information.
Following informaiton from old vfs website without editing.
GUIDANCE SHEET FOR BUSINESS TRAVELLER / TOURIST / FAMILY VISIT
Visa Class: B1/B2.
Page 1 of 3
ON THE DAY OF INTERVIEW:
Please be at the Visa Hall entrance, not more than 15 minutes before your appointed time.
SUPPORTING DOCUMENTS REQUIRED FOR THE INTERVIEW:
1. Passport, visa fee receipt issued by HDFC bank and interview appointment letter.
2. Original Birth Certificate for children below 14 years of age.
3. If you are visiting a relative, carry photocopies of the relative’s proof of status e.g. Green
Card, naturalisation certificate, valid visa etc.
4. National of foreign countries may be required to pay an Issuance Fee. To check the
availability as well as the issuance fee amount, log on to
www.travel.state.gov/visa/reciprocity/index. The fee if any needs to be paid via demand draft
in INR at the prevailing Consular rate of exchange.
Note: Mention your Name and Passport number on the reverse side of the demand draft.
5. Business travellers need to produce proof that the Company will finance the trip. If the
company is new or unknown it is helpful to carry tax records of the firm for the last 3 years.
6. It is also helpful to carry evidence of how the trip will be financed along with letters of
deputation, invitation or sponsorship .
7. A tourist may show evidence of financial resources through bank statements and tax returns
for the past 3 years.
8. Dependents joining their spouse on-board ship need to carry their original marriage certificate
and entire wedding photo album along with the spouse’s visa copy.
9. For parents visiting a child resident in the US:
1 If child is an Indian citizen.
(a) Childs’s original birth certificate.
(b) Photocopy of all pages of child’s passport.
(c) Where the US visa of child has expired, photocopy of the renewed petition required.
(d) Where child is a legal permanent resident in USA, photocopy of the green card (front
and back) is required.
1 If child is a U.S. citizen.
(a) Photocopy of bio-data page of US passport or photocopy of Naturalization