С plt.ticklabel_format
:
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
x=[1,2,3,4,5,6,7,8,9,10]
y=np.array([1,1,1,2,10,2,1,1,1,1])*100000
ax.plot(x, y)
plt.ticklabel_format(axis="y", style="sci", scilimits=(0,5))
plt.show()