During inrush period, multiple misoperation accidents of differential protection of power components such as transformers and adjacent transmission lines happened, which seriously threatened the safe and stable operation of power grid. In the traditional misoperation analysis, only the transformer transient inrush current process is considered, and the electromagnetic transient interaction between the transformer and other nonlinear ferromagnetic components such as CT is hardly considered. In this paper, the variation rule of transformer inrush current waveform characteristic is analyzed at first, and the influence rule of secondary load and type of CT on inrush current is simulated by using the simulation Lucas model of industrial practical CT (P/PR). The results show that second harmonic proportion of the inrush current and the dead angle of the waveform depend on the saturation angle of the transformer core. The larger the saturation angle is, the smaller the second harmonic proportion is, and the larger the dead angle of the waveform is. The second harmonic proportion of the inrush current becomes larger, and the dead angle of sympathetic inrush becomes smaller after CT transfer. The change of the dead angle of the inrush depends on the size of the load resistance, which may become larger and may be smaller. The conclusion can provide guidance for improving the differential protection of transformers under the interaction of multiple nonlinear ferromagnetic components. This work is supported by Science and Technology Project of Guangdong Power Grid Limited Liability Company (No. GDKJXM20162461).