In this letter, the 3-degree of freedom (DOF) 3RPS-SPS parallel mechanism with active and passive branches is proposed to use a single active input to realize the expected position adjustment, which can reduce its manufacturing and maintenance costs. The principle of motion of the 3RPS-SPS parallel mechanism is described. To lay the groundwork for the subsequent analysis, the forward and inverse kinematics models for the 3RPS-SPS parallel mechanism are established. Due to workspace and joint angle limitations, optimization of the adjustment sequence for the passive branches and driving step size is necessary. Finally, a prototype is designed and constructed, and experiments are conducted to validate the motion adjustments. The broad potential applications of the mechanism, particularly in scenarios where real-time positioning is not critical for heavy-load component adjustments, are highlighted.