How do i get my parents let me go visit my guy friend?

Build some trust with them. You said they think he is nice, right. So give them MORE reasons to want to like him. and let them confide in you, and know that you are the daughter they love and know. It takes time but first ask them if HE can come over to your place a couple of times and show them that you're just friends and nothing more. If this all doesn't work out, go to his house with aclose friend of yours and send her away i guess if she doesn't mind/!??