This paper presents a study on the design parameters of a permanent magnet (PM) biased magnetic actuator (MA) for improving stiffness and linearity of the system by using a dimensional analysis. To reduce the number of parameters and to generalize the results for similar systems, the design parameters were non-dimensionalized by significant variables characterizing the system. For the study, a 1-DOF PM-biased MA was built and the magnetic circuit model including leakage paths and core material reluctances was set up. The dimensional analysis shows that the dimensionless permanent magnet thickness is the key parameters for the linearity of the magnetic force and constancy of coil inductance and PM magnetic flux and that the non-dimensional leakage resistance is a main factor for the bound of the efficiency and the linearity.