All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is more appropriate for you to try your best to convince your parents to accept your studying Sharee'ah sciences in order to combine between obeying them and studying the Sharee'ah. Now, if they refuse without a legal excuse, and if the knowledge you are seeking is about individual obligation and there is no other way to get this knowledge, then there is no objection to your studying without their consent provided you adhere to all the rulings concerning women, like wearing the Hijaab and never staying in seclusion with non-Mahram men and provided this will not cause you any harm like being chased away by your parents from the family's home. If they object to your studying for a legal reason like their need for your house work and services, or if the knowledge your are seeking is among the communal obligations, or a supererogatory knowledge, then it is unlawful for you to go out without their consent and you could get satisfied with cassettes, books and your attendance of a lesson or two that your parents accept you to attend.
Allah knows best.