1. Install python and configure environment variables.
Go to the python official website to download: https://www.python.org/downloads/, I downloaded python2.7.14.
2. Install jdk and configure environment variables.
Go to oracle official website to download: http://www.oracle.com/technetwork/java/javase/downloads/index.html, I downloaded jdk7.
3. Download eclipse and unzip it.
Eclipse download address: https://www.eclipse.org/downloads/packages/all, I downloaded mars 2.
4. Download the pydev offline installation package
pydev download address: http://www.pydev.org/download.html, click SourceForge download at the bottom 
of the page to download, you can see the corresponding version that should be downloaded on the page:
Need to use older Eclipse/Java/Python
If you need to use an older version of Eclipse/Java/Python, below is the latest PyDev version to be used based on your requisites.
- Eclipse 4.5, Java 8: PyDev 5.2.0
- Eclipse 3.8, Java 7: PyDev 4.5.5
- Eclipse 3.x, Java 6: PyDev 2.8.2
- Python 2.5 or older: PyDev 5.5.0
Personally, if Jdk 8 is installed on the machine, download pydev 5.2.0, if Jdk 7 is installed, download pydev 4.5.5, if Jdk 6 is installed, download pydev 2.8.2. I have jdk 7 installed locally, so download pydev 4.5.5:
5. Install the downloaded plugin to eclipse
Open the directory where eclipse is located, enter the dropins directory, create a new eclipse directory, and create a new features directory and plugins directory in this directory: 
After decompressing PyDev 4.5.5.zip, copy all the files and folders in the features directory to the newly created directory. features directory, copy all files and folders in the plugins directory to the newly created plugins directory.
6. Configure the python executable directory.
Open eclipse, click [New] on the window -> preferences -> PyDev -> Interpreters -> Python Interpreter page.
Then, click [Browse], select the installation path of python.exe, and then click [ok] all the time.
Since then, you can use eclipse to write python code.