The work aims to propose a novel 4-DOF 3-translational-1-rotational (3T1R) parallel robot mechanism to meet the needs of sorting in automatic production line. The kinematic properties of the parallel mechanism were verified according to the design theory of orientation feature set. Based on the configuration characteristics of the mechanism, the kinematics equation model was established, and the forward and inverse position solutions of the mechanism were analyzed. The workspace figure and rotation capacity contour map of the parallel mechanism were obtained by numerical method. At the same time, the Jacobian matrix JX and singularity of the parallel mechanism were analyzed. Finally, with the maximum workspace as the fitness function, the structure size of the mechanism was optimized based on genetic algorithm. The operating space of the mechanism had the characteristics of regular shape, no cavity, large size, and good motion flexibility in the operating space. The workspace performance of the optimized parallel mechanism was increased by 45%. The kinematic dexterity in the workspace is good. The performance of the workspace is significantly improved after optimization. It has a good application prospect in the field of electronic packaging automatic production line handling and sorting.