Abstract: The magnetic field around a wire-array load of Z-pinch is essential to understand the wire-array ablation and ablated plasma flowing, as well as the following implosion processes. All the currents of the wire-array, return-posts, anode and cathode were divided by many small current lines or current surfaces, whose magnetic field were calculated by the formula of Biot-Savart’s law. The total magnetic field was obtained by summing all the fields contributed from all the current elements. The magnetic field contributed only by the wire-array currents deflects from the formula values of a long straight wire, while the total magnetic field is close to the formula values. The uniformity of the magnetic field in the region of the load can be improved by increasing the wire numbers, due to reduce