A simulation program with integrated circuit emphasis (SPICE) circuit model of voltage excitation fluxgate was proposed. It used the arctangent function to describe the hysteresis loop of fluxgate core, the excitation and measurement coils of the fluxgate were equivalent to a circuit model that contains a kind of non-linear time-varying inductance. Moreover, the expression of non-linear time-varying inductance has been given, which resolved fluxgate modelling itself into solving non-homogeneous ordinary differential equations with variable coefficient, and then the authors used HSPICE to solve the differential equations. The input and output characteristics of the dual-core fluxgate were simulated by this SPICE model. The results show that the model can better simulate the input and output characteristics of actual fluxgate, which verifies the validity of the model.