How does a student in haiti qualify for US visa?

I will assume that your sister applied for a visitors visa to the US. Such visas are given in the discretion of US consular officers taking into account the circumstances of the applicant including age, job, resources, property and other ties in the home country. Your being a US citizen could be seen as a negative factor on the question of whether your sister has nonimmigrant intent. I suggest that your sister strengthen her application by having more ties to the home country and be prepared to show those ties to the US consular officer the next time that she applies for the US visa.Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.