Method for optimizing residual magnetism measurement process in magnetic resonance imaging system

The invention discloses an optimization method for a residual magnetism measurement process in a magnetic resonance imaging system, and the method comprises the steps: employing a positive and negative combined gradient as a test gradient, measuring the change of the uniformity of a magnetic field caused by the test gradient in combination with the difference of the effects of the heterogeneity of the magnetic field on spin echoes and gradient echoes, and achieving the optimization of the residual magnetism measurement process. And the intensity of the residual magnetism is measured by using the change of the echo peak value caused by the change. According to the method, benchmark testing under the condition that the testing gradient is zero is avoided, the adverse effect of the hysteresis effect on the benchmark signal is overcome, it is guaranteed that the magnetic field distribution state is determined and stable when echo signals are collected in the measuring process, the influence of the testing sequenc