In order to realize nondestructive testing of ferromagnetic objects, a magnetic field scanning system based on FPGA and magnetic sensor array is designed. FPGA is the main controller of this system that includes AD configuration module, AD interface module and data cache module. FPGA controls the transmission device to scan, and the magnetic field is converted to the corresponding voltage signal by the magnetic sensor array and the circuits. The voltage signal is transmitted to FPGA through the analog-to-digital conversion module with the core of AD7768, and high-speed magnetic field data acquisition system with eight parallel channels is realized. Then, through bilinear interpolation and pseudo-color conversion algorithm in FPGA, the collected magnetic field data are converted to the image of magnetic field distribution, which is stored in SD card and displayed in LCD in real time. In the experiment, the magnetic field scanning system is used to carry out magnetic field scanning for the ring magnet, magnetized wire, iron nails embedded in the wood plate, wire stripping pliers and needle-nose pliers. The program, based on magnetic flux and OTSU method, is used to locate and identify the object. The average root mean square error of positioning is 3 mm, and the measured length is close to the length of the actual object. The position and direction of the magnetic object could be identified, and the magnetic object could be identified by the characteristic magnetic field of the object, so as to achieve the purpose of nondestructive detection and identification of ferromagnetic objects. FPGA ZYNQ7010, AD7768, HMC1001 are used to collect magnetic field data in the system. It has the advantages of high acquisition rate, convenient expansion, low power consumption, and can obtain magnetic field image with spatial distribution . It can be applied to the location and recognition of ferromagnetic targets, such as safety detection, magnetic target detection of underground and underwater.