Planar wire arrays have been widely studied as a kind of non-cylindrical wire array load in recent years. In this paper the magnetostatic simulation of individual wire in a planar wire array is performed using a radial motion equation in order to understand the patterns of the current partition through the wires, the force distribution on the individual wire, the magnetic field distribution on the planar wire array, and the variations of the total load inductance and the kinetic energy of the wire array during the implosion phase. The model has also been used to calculate the implosion trace and time of the planar wire array used on "Qiangguang-Ⅰ" generator. The calculation results are compared with the experimental results and it is concluded that the model gives an implosion time with an error of about 10%. All the simulation results mentioned above can help one further understand the process of the planar wire array Z-pinch and design the load parameters.