I am a muslim alhamulellah and I have a question regarding marriage.

I like a girl and I want to marry her but my parents do not agree with our marriage so without the agreement of parents will it a valid marriage according to the law of Islam.

Wasalam

Yes the girl needs permission of her parents to get married. Also girl has the right not to accept any proposal, so parents cannot force the girl to marry anyone.
The girl needs to speak with her parents and ask them to allow to get married with you.
Running away and getting married without their permission wouldn't be considered a marriage. In the last resort you can involve a qazi and ask them to ask as a arbitrator and convince the parents to get her married with you.

You can also ask the qazi to act as a wali if parents of the girl don't have any genuine reason in not allowing your marriage