Abstract: Estimation and simulation of submarine’s magnetic field are of practical significance to the development of decoy, aiming target, and magnetic field simulation detection instrument. This paper analyzes the rotary prolate spheroid model and the magnetic dipole model, and estimates the magnitude of submarine magnetic field. Comparing the magnetic fields of hollow sphere and solid sphere with high permeability, a method of applying hollow permanent magnet to simulation of submarine magnetic field is proposed, and the essential parameters of the permanent magnet are estimated with this method. This method may be taken as a tool in theoretical research and experiment of submarine′s magnetic field detection and in realization of the submarine′s magnetic field simulation for decoy and aiming target.