Three different kinds of valve spool structures of single-coil magnetorheological(MR) valve were designed according to the rheological properties of MR fluid. The pressure drop properties of single-coil MR valve were calculated and analyzed. Meanwhile, three different kinds of valve spool structures of MR valve were simulated using ANSYS software. The distribution of magnetic flux line, magnetic field intensity as well as the magnetic induction of flow path were obtained. The influence of the valve spool chamfer, input current and flow rate on the pressure drop were studied. The results show that the pressure drop is increased with the increasing of the input current and the flow rate for the three different valve spool structures, and the pressure drop with the plain ends is bigger than those of with the chamfered ends and the filleted ends. The relevant conclusions have a certain guiding significances for the structure design of MR valve.