This paper presents a dual screw actuation mechanism (DSAM) wherein two screws actuate the common sliding platform by connecting two screw nuts with a gear pair. Two dimensionless parameters, namely, the gear ratio between two gears and the pitch ratio between the two screws, are defined to describe the structural characteristics of the DSAM. This study investigates the performance characteristics of a DSAM with respect to gear ratio and pitch ratios. The load distribution between the two screws, which is important in planning the contributions of the two inputs during operation, is discussed. The load capacity is deduced according to the load limits of the two screws with the actuator. The analytical expression for the overall mechanical efficiency of the DSAM is derived from the normal operational power flow mode (two-input-one-output). Based on the Lagrangian formulation, the dynamic coupling term that evaluates the extent to which the inertia torque of one input is affected by the motion variations of the other input is obtained. This performance study provides the fundamental guidelines for the design and operation of a DSAM.