self.button.setStyleSheet("QPushButton{background-image: url(img/1.png)}")

self.button.setStyleSheet("QPushButton{border-image: url(img/1.png)}")

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton
 
class Example(QWidget):
 
 def __init__(self):
  super().__init__()
 
  self.initUI() # 界面绘制交给InitUi方法
 
 def initUI(self):
  # 设置窗口的位置和大小
  self.setGeometry(300, 300, 300, 220)
  # 设置窗口的标题
  self.setWindowTitle('QPushButton')
 
  #控件QPushButton的定义和设置
  self.button = QPushButton(self)
  self.button.setStyleSheet("QPushButton{border-image: url(img/1.png)}"
         "QPushButton:hover{border-image: url(img/1_1.png)}" 
         "QPushButton:pressed{border-image: url(img/1_1.png)}")
  #设置控件QPushButton的位置和大小
  self.button.setGeometry(100, 100, 50, 50)
 
 
 
 
if __name__ == '__main__':
 # 创建应用程序和对象
 app = QApplication(sys.argv)
 ex = Example()
 ex.show()
 sys.exit(app.exec_())

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton
 
 
class Example(QWidget):
 
 def __init__(self):
  super().__init__()
 
  self.initUI() # 界面绘制交给InitUi方法
  self.slot_init()
 
 def initUI(self):
  # 设置窗口的位置和大小
  self.setGeometry(300, 300, 300, 220)
  # 设置窗口的标题
  self.setWindowTitle('QPushButton')
 
  #控件QPushButton的定义和设置
  self.button = QPushButton(self)
  self.button.setStyleSheet("QPushButton{border-image: url(img/1.png)}"
         "QPushButton:hover{border-image: url(img/1_1.png)}")
 
  # 设置控件QPushButton的位置和大小
  self.button.setGeometry(100, 100, 50, 50)
 
 def slot_init(self):
  self.button.clicked.connect(self.button_change)
 
 def button_change(self):
  # 切换图标变亮
  self.button.setStyleSheet('QPushButton{border-image:url(img/1_1.png)}')
 
 
 
if __name__ == '__main__':
 # 创建应用程序和对象
 app = QApplication(sys.argv)
 ex = Example()
 ex.show()
 sys.exit(app.exec_())