The double drive closedloop mechanism has the advantages of simple and compact structure, better flexibility and bigger workspace, so it can be used to design parallel mechanisms. Based on the theory of position and orientation characteristics (POC) equations, a systemic approach of type synthesis for spatial parallel mechanisms containing planar closed-loop structures within limbs was proposed, consequently numerous novel parallel mechanisms consisting of fewer limbs were synthesized by using this technique. Firstly, the topological compositions and equivalent outputs of seven kinds of dual drive loops were presented and analyzed. Then, the 3T1R, 3T2R and 3T3R chains with dual drive five-bar loop were generated. Based on the complex chains synthesized, three kinds of three-chain and two kinds of two-chain 3T1R parallel mechanisms, two kinds of four-chain and four kinds of three-chain 3T2R parallel mechanisms, as well as two kinds of four-chain and two kinds of three-chain 3T3R parallel mechanisms were constructed. Furthermore, the topological characteristics of these fifteen kinds of mechanisms were analyzed, including the number of the independent loops, number of over-constraints and coupling degree. The results showed that the mechanisms with fewer limbs had not only the characteristics of simple, compact and symmetrical structure, but also had the low coupling degree to facilitate the kinematic and dynamic analysis, which made these mechanisms promising prospect in the application of industry. This work contributed to enriching and improving the structural synthesis theory of the parallel mechanisms with fewer limbs.