这个是版本问题，官方已给出答案

如果要用pydev 5.0 JDK 必须 1.8，1.7是不行的。

PyDev does not appear after install!

Well, the main issue at this time is that PyDev requires Java 8 in order to run. So, if you don't want to support PyDev by going the LiClipse route (which is mostly a PyDev standalone plus some goodies), you may have to go through some loops to make sure that you're actually using Java 8 to run Eclipse/PyDev (as explained below).