Abstract: The magnetic field full tensor detection is a promising technique for the multi-magnetic source inversion. The cross-shaped magnetic gradient tensor structure is widely used for its simple calculation, high precision and other desirable characteristics. But the systematic error analysis and the correction methods in the multi-magnetic source inversion field remain to be improved. This paper studies the multi-dipole discrimination, analyses the calculation structure and the error sources of cross shape. It is shown that the magnetometer precision, the overall structure, the background environment and the baseline selection will all cause errors, and even lead to mistakes. The correction methods and suggestions are then proposed, as well as a feasible scanning method.