Traditional parallel manipulators suffer from errors due to backlash, hysteresis, and vibration in the mechanical joints. In this paper, a new 3SPS+RPR spatial compliant mechanism which has three degrees of freedom (DOF) and can generate motions in a microscopic scale is proposed. It can be utilized for biomedical engineering and fiber optics industry. The detailed design of the structure is introduced, followed by the performance evaluation. Then, the genetic algorithms and radial basis function networks are implemented to search for the optimal architecture and behavior parameters in terms of global stiffness/compliance, dexterity and manipulability.