A computer simulation complex for magnetic gradiometry systems is described. This complex simulates the estimation procedure for the magnetic dipole moment of a moving object according to the magnetic gradiometry data. The paper considers the software architecture and intended purpose of the complex and the algorithms of its modules, including the magnetic field module, the ambient magnetic field module (the object’s magnetic field, the main magnetic field, the magnetic anomaly, and industrial magnetic noise), and the magnetic dipole moment module. Some numerical experiments with the simulation complex are briefly described. This complex can be used to design degaussing systems for the magnetic field of moving objects.