This paper presents the design of a selective-actuation flexure parallel mechanism that can provide three independent translational motions. The mechanism can be used as an ultra precision positioning system. The modeling of the flexure parallel mechanism is then established based on a pseudo-rigid body model and the compensation of the flexure deformation. The factor of deformation allows us to formulate accurately the position control of the flexure mechanism. The dimension and free shape of the mechanism are determined based on the criteria of isotropic resolution transmission scale. The experiment shows the advantage of the proposed model versus the currently used model. The experiment also proves the validity of the resolution evaluation and the optimization.