Focused on the similarity between the kinematics of decoupled parallel mechanism and serial mechanism, a unique method of structural synthesis was presented, which was used to synthesize the decoupled parallel mechanism. The kinematic chains of decoupled parallel mechanism were consisted of by the basic kinematic chain and the driven-chains. The structural condition of decoupled spherical parallel mechanism was deduced, and a series of novel spherical parallel mechanism were synthesized. The kinematics analysis verified that the mechanism had three fully decoupled rotational DOFs, and each rotational DOF was driven by a single actuator.