Petition for my father after 10th year outside of USA, he stayed 14 years in the United States as a illegal

Assuming that your father is not barred for any reason other than being in the US for one year or more illegally, he should be able to immigrate provided there is no problem with financial support. He may be asked about his marriage to the American citizen as an attempted fraudulent marriage would be a permanent bar. 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.