You may sponsor your sister, but keep in mind that she will have to wait for the visa to become available to her. Depending on the country of nationality, the waiting time for the visa may be ten years or more.
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Your sister will have to wait over 10 years to get a green card through you and must maintain lawful status all the time to get it without leaving the US. Once you filed the petition, it will be more difficult for her to re-enter the US on a visa because your petition indicates that she wants to live permanently in the US.
You can petition your sister however it will take a very long time for her priority date to become current. This varies based on country of origin. As others suggested, a ten year wait is not uncommon.
As your sister is a student she must also consider how long she intends to remain in school. Once she has expressed immigrant intent to the US government she will no longer be eligible for student visas and will have a difficult time obtaining temporary work visas.
It will be a long wait, about 10 years for her to get residency. Also if you wish she adjust status, she should maintain status for all these years.
This response is general in nature and cannot be construed as legal advice, given that not enough facts are known. Any comments offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship. If you would like additional information based on this response, please contact my office at 510 657 7665 or 415 902 0832 to schedule a consultation.