In view of the disadvantages of the viscosity coefficient measurement experiment by the falling ball method:it is difficult to ensure that the ball is released from the center，and the manual timing error is large， the viscosity coefficient measuring instrument is improved．With the help of the automatic lifting ball release device，it is convenient to adjust the initial position of the ball and ensure that the ball is released from the center of the liquid surface;the metal detector can monitor the falling displacement of the ball in real time．The design of the sealing plate and the discharge pipe can achieve the collection effect of the liquid． The experimental results show that the measured value of viscosity coefficient by the modified device has less error，higher reliability and more accurate experimental results．