This paper studies the changes of the transformer equivalent circuit model parameters in the saturation of iron core when the transformer closes to power system without load, and by analyzing the characteristics of inrush current in different situations, points out the limitation of the traditional method to identify inrush current. By optimizing the combination of traditional methods and adding the new CT saturation recognition criteria, it establishes a set of multi characteristic inrush current identification scheme. By the simulation analysis of inrush current in different situations, it verifies the correctness of the scheme:such as closing transformer breaker in one side with high remanence and at the voltage near zero-cross, with low remanence, and without remanence, the scheme in this paper can correctly identify the inrush current by multiple methods cooperating with each other and reliably locking the differential protection; when closing to the fault transformer with CT saturation, the scheme can also unblock the differential protection with the CT saturation criterion.