In this paper, a sitting-type lower limb rehabilitation robot with a parallel manipulator system integrated is proposed. This study discusses the proposed design and development of the manipulator as well as its kinematic information. The lower limb’s rehabilitation procedure is described. The goal of the prototype experiments is to validate the suggested concept for therapy use of 4PR parallel manipulator also forward and inverse kinematic analysis has been investigated in this study. Massive prismatic actuators are replaced with SMA spring-based actuators. Additionally, using experiments, a thorough analysis of the actuator displacement or deflection of the Shape Memory Alloy (SMA) spring-based actuators in the use of moving the manipulator has been presented. According to the experimentally obtained data, SMA spring-based actuators have a higher workspace. Overall, this study demonstrates that using 4PR parallel manipulator with Shape Memory Alloy spring as an actuator is the best alternative than using usual weighty actuator for motions. Note: P stands for prismatic joint and R stands for rotary joint.