This paper represents the introduction to the Magneto Rheological (MR) fluid and its basic properties. The main aim of this paper is to prepare the magneto rheological fluid for the MR damper which is used in vehicle suspension system. MR fluids are a class of smart material. A MR fluid is a very useful constituent material for the engineers which are involved in the design of brakes, damper, clutches and shock absorber system. This paper also emphasis on the details of preparation, testing and validification of magneto rheological fluid for its effective use and testing of MR damper. Now a days increasing vibration affect the vehicle ride comfort. To improve ride comfort of vehicle suspension system magneto rheological fluid is very necessary in magneto rheological damper to reduce the vibrations or shocks.