Mobile parallel robots (MPR), which structurally configured a moving platform and several parallel limbs with an actuating wheel at the end of each limb, exhibit advantages in high mobility, high load capability and high flexibility in complex task environments. In this paper, a 6-DOF MPR with 3-PPUU (Prismatic-Prismatic Universal-Universal) limbs is proposed. The structural scheme and inverse kinematics are first presented; the orientational workspace and the dexterity of the MPR are analyzed in detail. A parametric optimal design model is then developed; the optimal scheme of the MPR is obtained. The constant-posture control scheme and algorithm are also proposed in this paper. A prototype of the 3-PPUU MPR with omni-orientational wheels is developed and the precision for both translation and orientation of the prototype is measured by experiments, which verify the feasibility of the proposed MPR scheme.