The stick-slip motion of magnetorheological (MR) fluids under a simple linear shear mode has been experimentally reported. The critical shear strain for the onset of the stick-slip motion decreases logarithmically with the magnetic flux intensity applied. The rate of energy accumulation and releasing during stick-slip motion changed in a power law of the viscosity of the continuous phase in a range of 0.01 similar to 1000 mPa S. Different carrier fluids led to different stick-slip characteristics. The stick-slip motion can be fully suppressed with certain carrier fluids. When the MR fluids are in a shear-thickening state, the critical shear strain of the onset of the stick-slip motion is larger than a normal state. But, the relative spike amplitude of the stick-slip remains similar.