A series of hybrid kinematic chains containing 2-transla-tional and 1-rotational （2T1R） kinematic outputs were constructed. Ten new types of 2T1R spatial parallel robot mechanisms were obtained based on the single-opened-chain （SOC） unit theory. All the new mechanisms actuators are directly mounted on the bases or near the bases

which contributes to decrease mechanisms’ inertia. The fundamental characteristics of the mechanisms

such as the attribution of the actuators

coupling degree and kinematic decoupling

were analyzed

which provides references for the optimal selection of the mechanisms synthesized here.