如果你想用英语表达"姐姐不让我出门"，可以说"My sister won't let me go out."

其中，"won't"是"will not"的缩写，表示否定。例如，你可以说：

I won't go to the party if you don't want me to. (如果你不想我去，我就不去聚会了。)
She won't psten to what I have to say. (她不会听我说什么。)
They won't be able to finish the project on time. (他们不可能按时完成这个项目。)

另外，"let"在这里表示"允许"或"让"的意思。例如：

Can you let me borrow your pen? (你能让我借你的笔吗？)
He won't let me see his phone. (他不让我看他的手机。)
She lets her children do whatever they want. (她让孩子们做任何他们想做的事。)