You're missing the call to the show() function that will display the plot items.
import pandas as pd
from numpy import *
import matplotlib.pyplot as plt
ts = pd.Series(random.randn(1000), index=pd.date_range('1/1/2000', periods=1000))
ts = ts.cumsum()
ts.plot()
plt.show()
PyCharm is more than likely not configured in interactive mode with matplotlib.