L1 is a working class visa for the United States of America. Upon receipt of the approval on the L1 visa petition, your original documents would be required to be submitted. Under mentioned are the list of documents that would be required for the same.

1. The first requirement for the L1 visa would be a completed DS 156. This is the non immigration visa application form.
2. The next document in line that would be required would be the DS 157. This should also be completed in all respect.
3. Original receipt of the visa fee paid. This receipt would be issued by HDFC bank. (The HDFC bank would be applicable only if the application is from India).
4. A copy of the appointment letter for the interview at the embassy. This should be obtained at the time when the appointment was set up originally at the VFS.
5. A valid passport would also be required. Please note the passport should have a validity of more than six months at least.
6. A copy of the latest resume of the applicant would be required.
7. A copy of the original L1 petition that was submitted to the USCIS at the time of applying for the L1 visa.
8. A letter would also be required from your employer to the consulate would also be required, requesting for a L1 visa for your, it should also have details about your employment in the United States.
9. The above mentioned letter should be accompanied with all the other legal paper work that you should have received from your employer in the United States.
10. 2 photographs would be required, the specification for this is that, the photos should be 2” by 2” (50mm) square in shape, there should be no head covering, the background should be absolutely white in color. Please note that the United States consulate is extremely particular about these photographs. But you need not worry; any photo studio you visit would be doing it for you, if you tell them that it’s for the United States embassy.
11. Last but certainly not the least; you would be required to attach the demand draft for the visa issuance fee. You can know about the latest applicable rates either from the bank or from the net.

Being prepared with the above mentioned documents, would make your experience smooth at the United States consulate.