But i m on F 1 visa and my mom try to come on visitor visa and she has intension to stay illegally that i know only but how can i do to prevent this ?

Your mother is her own person and I imagine that she will do whatever she wishes concerning her own immigration status. You are not liable for the actions of your mother unless you are conspiring with her to have her come and stay illegally in the country. The immigration laws do not assign any form of penalties against relatives in cases like the one you describe. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (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.