Is it okay to tell my parents about my younger brother's binge drinking?
Why do you think it's necessary to tell your parents about this?
Because my younger brother likes to drink a lot.
I'm sorry your brother is struggling.  It's good of you to want to bring this to your parents attention so he can get the help he needs with this.  Being concerned like you are shows you love the guy!
You think?
You are a good brother and even if they don't know it or appreciate it now, they will later in their life. Telling your parents is the right thing and they will be able to help your brother's drinking problem.