The invention relates to a method for measuring viscosity, in particular to a method for measuring the viscosity of dynamic fluid by using a vibration pipe, a controller, a flow rate detecting device and a calculating device, wherein the vibration pipe is communicated with a fluid flow pipeline, the controller is used for controlling the vibration of the vibration pipe, and the flow rate detecting device and the calculating device are respectively arranged on two ends of the vibration pipe. Because a Coriolis mass flowmeter can be used for directly measuring the mass flow rate of the fluid, the dynamic viscosity measurement result with the flow rate compensated can be calculated conveniently, and further the viscosity of the fluid can be measured on line in real time. Because the Coriolismass flowmeter can be used for measuring the density of the fluid in the pipe, the real-time kinematic viscosity of the fluid in the pipe can be obtained.