The 6-branch chain parallel platform has complex positional constraints and is prone to damage to the mechanical structure when the control algorithm fails. Therefore, the kinematic operability and workspace of a 3UPU-UP parallel platform was analysed. Firstly, the kinematic model of the 3UPU-UP parallel platform was derived through the analysis of vector method and kinematics, based on which, the evaluation index of the operability of the tandem robotic arm was firstly combined with the characteristics of the mechanism structure of the 3UPU-UP parallel platform. The operability of the 3UPU-UP parallel platform was computed, analyzed and visualized. The Monte-Carlo method was combined with the orthogonal kinematics to analyze the workspace of the 3UPU-UP parallel platform. The Monte-Carlo method and positive kinematics were combined to calculate, analyze and visualize the workspace of the parallel platform. The workspace of the parallel platform can be expressed more intuitively and completely. The research results provide the theoretical basis for the design of the 3UPU-UP parallel platform and confirm its theoretical feasibility.