方法如下：
找到安装路径下有个属性文件，我的是在 D:Program FilesJetBrainsIntelliJ IDEA 2017.3.2in 进入bin目录后找到属性文件：idea.properties 用记事本或者Editplus 将其打开，找到如下代码段：
- # path to IDEA config folder. Make sure you're using forward slashes
- idea.config.path=${user.home}/.IntelliJIdea/config
- # path to IDEA system folder. Make sure you're using forward slashes
- idea.system.path=${user.home}/.IntelliJIdea/system
- # path to user installed plugins folder. Make sure you're using forward slashes
- idea.plugins.path=${user.home}/.IntelliJIdea/config/plugins
发现其中包含3个路径 idea.config.path和idea.system.path和idea.plugins.path 这个就是设置了文件的存放路径，那么我们将 ${user.home} 替换为我们自定义的路径就好了，替换 如：D:Program FilesJetBrainsIntelliJ IDEA 2017.3.2 ，注意“/”的方向。修改后的如下：
- # path to IDEA config folder. Make sure you're using forward slashes
- idea.config.path=D:/Program Files/JetBrains/IntelliJ IDEA 2017.3.2/.IntelliJIdea/config
- # path to IDEA system folder. Make sure you're using forward slashes
- idea.system.path=D:/Program Files/JetBrains/IntelliJ IDEA 2017.3.2/.IntelliJIdea/system
- # path to user installed plugins folder. Make sure you're using forward slashes
- idea.plugins.path=D:/Program Files/JetBrains/IntelliJ IDEA 2017.3.2/.IntelliJIdea/config/plugins
然后发现D:/Program Files/JetBrains/IntelliJ IDEA 2017.3.2 路径下出现了 .IntelliJIdea的文件夹，修改成功！以后在使用时就不会占用C盘啦，C盘C:UsersAdministrator.IntelliJIdea90 的文件夹就可以删除了。快去试试吧！