Abstract A novel symmetric parallel mechanism 6RPS with multi-redundant actuations is proposed in this paper, which possesses two rotational and one translational degrees-of-freedom. Motion and constraint screw systems of this mechanism are established and then character of the freedom is analyzed. Transmission performance indexes are established, and dimension optimization is operated by considering the distribution of transmission performance. Whole high-performance workspace and performance distribution are analyzed with optimal dimension. Motion interference condition of the mechanism is studied, and accessible posture spaces are analyzed by combining joint space restriction. A comprehensive performance comparison with a counterpart configuration is exhibited. Research results of this paper are of reference significance for both the research of parallel mechanism with two rotational and one translational degrees-of-freedom, and the application of mechanism 6RPS.