Parallel kinematic mechanisms with serve-hydraulic actuation can provide multi-degree of freedom (DOF) motion with unequalled power output and dynamic response. A good example is the hydraulic Stewart platform typically used for flight simulator motion systems. This paper considers parallel servohydraulic mechanisms in which the hydraulic cylinders form legs which connect a base to a table. Their design involves balancing a number of conflicting requirements: The geometry of the mechanism dictates the length of the cylinders which in turn dictates a maximum actuator stroke, and hence a maximum table displacement. The geometry also dictates how the velocity and force requirements for the table translate into velocity and force requirements for the actuators, determining actuator sizing and the hydraulic flow requirements. The size of the actuator determines its mass and inertia properties, as well as its hydraulic stiffness, and will influence the resonant frequencies of the table. These frequencies in turn affect the achievable closed-loop bandwidth. A design method is proposed which allows one parameter to be optimised whilst adhering to the other design constraints. A detailed example is presented for a 2 DOF mechanism.