Right-click on the module, select "Add framework support...", and check the "Maven" technology.
(This also creates a pom.xml for you to modify.)
If you mean adding source repository elements, I think you need to do that manually–not sure.
This does not convert the project to use the Maven Standard Directory Layout.
Intellij IDEA 普通项目添加Maven支持,布布扣,bubuko.com
原文：http://my.oschina.net/CasparLi/blog/300611