: Homogeneous magnetic field is necessary in NMR magnet. In general shimming magnetic field is by experience. So it’s difficult to shim. It depends on experiences frequently. Artificial Neural Network based on the ANN toolbox of Matlab is put forward to apply in the process. Error backward propagating network is created. The method is varied from different uniformity of magnetic field. The neural network consists of two subnets—coarse regulating network and fine regulating network which are trained respectively. After the model is established, shimming magnet becomes rapidly and accurately. The ferromagnetic shim needn’t be tried many times and aimlessly. It is judged only once. Magnet shimmed by ANN has a nice uniformity and can meet the condition of NMR core Analyzer well.