1. Start Eclipse Editor
2. Click in Help > Install New Software
3.Then Click in Add and use the entries as shown below
Name : PyDev Eclipse
Location : 
http://pydev.org/updates/
Click on Ok.
Then wait for few seconds, the list will be updated and you’ll be presented with two options
PyDev and PyDev Mylyn Integration(optional).
Select the upper one. Then click Next > Finish.
When asked to trust the certificate from Aptatna Tick the box next to it, then Eclipse will download the plugin.
Q. How to confirm plugin installation has succeed ?
A. Click File > New > Other
PyDev is also listed, that confirms the installation of PyDev has succced.
Have a nice day.
-Asee
Reference: http://marketplace.eclipse.org/content/pydev-python-ide-eclipse