import matplotlib.pyplot as plt
from PyQt5 import QtGui

plt.plot([1,2])
# 构建图标
PATH_TO_ICON = r"c:\quit.png"
new_icon = QtGui.QIcon(PATH_TO_ICON)
# 方法一：使用figure.canvas.manager获取当前图像的`FigureManagerQT`类实例
fig =plt.gcf()
fig.canvas.manager.window.setWindowIcon(QtGui.QIcon(new_icon))

# 方法二：使用plt.get_current_fig_manager()获取当前图像的`FigureManagerQT`类实例
plt.get_current_fig_manager().window.setWindowIcon(new_icon)
plt.show()

class FigureManagerQT(FigureManagerBase):
  """
  Attributes
  ----------
  canvas : `FigureCanvas`
    The FigureCanvas instance
  num : int or str
    The Figure number
  toolbar : qt.QToolBar
    The qt.QToolBar
  window : qt.QMainWindow
    The qt.QMainWindow
  """

  def __init__(self, canvas, num):
    FigureManagerBase.__init__(self, canvas, num)
    self.window = MainWindow()
    self.window.closing.connect(canvas.close_event)
    self.window.closing.connect(self._widgetclosed)

    self.window.setWindowTitle("Figure %d" % num)
    image = str(cbook._get_data_path('images/matplotlib.svg'))
    self.window.setWindowIcon(QtGui.QIcon(image))

def get_current_fig_manager():
  return gcf().canvas.manager