I'm a permanent green card holder and my us husband is in another country studying.Can i still apply for citizenship?

A naturalization application based upon marriage to a US citizen and being submitted in three rather than the usual five years requires that the couple have stayed constantly together with very little separation during the three-year period. In your case where your husband and you have been separated for one and a half years, you would have to wait for the five years. As you are probably aware, you are eligible to file for naturalization 90 days ahead of five-year limit. 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.