This paper presents the fabl'ication and study of rheology of A new mognctorheo1.ogical shcar thickening fluid (MR TF). Nlin size silica particles were suspcndcd in a solvent elhylene glycol, at high concentration which form hcar thickenjng fluids. Then the micron-size carbonyl iron particles .with different volume fractions were added into the TF to fabricaled MR TF. Their dynCllilie properties in different shear strain rate and magnetic field were tested by using a rheometer. The 1I. pension show an abnlpt Increase in complex viscosity beyond a critical dynamic shear rate and a magnetic field controllable charactcristic, as wel.l as rever ibl .