Because :
vue-cli3.0 defaults to using the yarn package management tool instead of the original NPM

In yarn, node-sass, the default download will most likely fail if you don’t over the wall

The solution

	yarn config set sass_binary_site http://cdn.npm.taobao.org/dist/node-sass -g

So when use the yarn to download the node – sass don’t stuck an error failed to install
this method not only solve the vue cli3 installation node – sass error
is used to solve the yarn package management tools installation node – sass error problem
Problem solving