relative path error? All image, css and js file not works.

I want to deploy the website to my xxx.github.io/blog, and I have cloned the repo to my `blog` repo. However, all link points to the root directory. For example, an image with src `/img/xxx.jpg` is pointed to 'xxx.github.io/img/xxx.jpg', not 'xxx.github.io/blog/img/xxx.jpg'. How to solve it?