Abstract: This paper studies the damping mechanism of a kind of micro-isolator, deduces the theoretical formula for the damping force of Newton nuid, and proposes the concept of effective diameteL Utilizing the software Fluent, simulations are carried out for the micro-isolator. It is shown that the damping force does not depend on the time of equivalent piston's movement, and compared to the frictional damping force, the local damping force is very small and can be ignored, then the theoretical formula of the damping force is obtained and validated. The value of the effective diameter is determined by the size of the danlping cavity and the correction coefficient, which can be used as a refbrence in the design of micro-isolator.