Based on the Stokes formula and Newton’s second law，this paper proposes a new method for measuring the viscosity of liquid-the floating method，and designs and fabricates an experimental device for the floating method．The idea of this experimental method is to combine the ball with the help of a magnet After being pulled to the center of the bottom of the container，it is released．Because the buoyancy of the combined ball is greater than gravity，the combined ball floats up． It can be observed that the combined ball performs a variable acceleration movement in castor oil with reduced acceleration until it reaches a constant speed． The uniform speed section of the combined ball is measured by a timing device．Calculate the viscosity coefficient of

castor oil．The principle of this experimental method is simple，the experimental equipment is reliable，and the experiment repeatability is high． It provides a reliable and effective new method for measuring the viscosity coefficient of liquid．Through this method The error between the measured and calculated viscosity coefficient and the standard value is less than 5%，indicating that the method has high measurement accuracy．