Problem:
Could not find any in this variable libyara.so Because it is a system variable and the directory is not writable

Solved :
As can be seen from pypi's official website, Yara has not been updated since 2014, but Yara Python has been released in 2020

Step1: install yara-python (yara.so)
pip install yara-python -i https://pypi.org/simple

Step2: copy "python2.7\site-packages\yara.so" to ida\python\yara.so

The size is 410k, compared with 96k in 2014
Success~

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