A systemic methodology for structural synthesis of fully-isotropic two-translational and one-rotational (2T1R) spatial parallel robotic manipulators was proposed. According to the prescribed characteristics of each mechanism limb, the actuation screws, actuated screws and mobile unactuated screws of every limb were confirmed at first based on the reciprocal screw theory. Then the structural synthesis of each kinematic chain for fully-isotropic 2T1R spatial parallel robotic manipulators was performed in the light of different connectivity of the limbs. Finally, the anticipant manipulators were synthesized by connecting the moving platforms to the fixed bases and a lot of new mechanisms were attained. Kinematical analysis about one of manipulators designed here showed that the method is reasonable and correct. The kinematic Jacobian of the mechanism is an identical matrix, so it performed very well with regard to motion and force transmissions.