In this work the normal force behavior of magnetorheological suspensions are systematically investigated. Four magnetorheological suspensions with different volume fractions (10%, 20%, 30%, and 40%) are prepared and both the static and dynamic normal forces of the samples are measured by using a commercial plate-plate magneto-rheometer under constant and sweeping magnetic field. A positive normal force will be generated when the applied magnetic field exceeds a critical value. The normal force firstly increases with the increasing of magnetic field strength and then reaches a saturation value. A magnetization model is utilized to represent this mechanism. The oscillatory dynamic normal forces with time are studied and their changes with shear rates are dependent on the volume fraction. Comparisons between static and dynamic normal forces show that the differences between them are dependent on the volume fraction and magnetic filed. The temperature effect on the normal force is studied and under high magnetic field the normal force would increase slightly with the increasing of temperature.