Taking the typical 3-RPS parallel mechanism as the research object, the performance change of the mechanism was analyzed when the structural parameters were changed. Based on kinematics analysis, the Jacobian matrix of the mechanism was derived. The condition number and the minimum singular value of the Jacobian matrix were used as the performance parameters. Two sets of structural parameters were selected, the condition number and singular value distribution of the Jacobian matrix in the ±30° space around the X and Y axes were calculated combined with MATLAB. The threedimensional mesh and the singular value distribution of the mechanical performance parameters were drawn. The results show that the smaller the ratio of the radius of the spherical pairs to the radius of the revolute pairs, the better the performance of the mechanism; an increase in two parameters will make the isotropic of mechanisms get worse. The research results provide a theoretical basis for the structural design and optimization of 3-RPS parallel mechanism.