In this research, we studied the manipulability of the wire harness connectors' mating process by dual-arm manipulation. Nowadays, we notice that collaborative or small-sized industrial robot manipulators attain high accuracy and repeatability levels (sub-millimeter); thus, they demonstrate exact position control capabilities. Using those capacities and with the correct method system, we can apply them to the automation of the wire harness mating process. We provided a method to calculate the parallel position of the end-effectors for a successful mating process with finding the maximum manipulability analysis. The experiments and results indicate that manipulability is an essential key for solving the parallel position of the wire harness connectors in the mating process, including obtaining the best and fast joint angles solution of the dual-arm manipulator for the mating process.