The invention discloses an iron-core coil low-power current transformer model in an electric power system and a modeling method of the iron-core coil low-power current transformer model. An iron-core coil low-power current transformer converts secondary current into voltage and outputs the voltage through a shunt resistor Rsh to achieve current to voltage (I/V)conversion. Shunting resistance is small so that power consumed by secondary winding is small, secondary power required by a load is small, and measuring ranges and accuracy are ideal. The iron-core coil low-power current transformer is large in measurement ranges and small in the size. The iron-core coil low-power current transformer model includes a sensing head unit, an amplification link, a phase shift link and a blocking link. The model is established on the basis of a CBuilder self-defining element development environment in a real time digital simulator (RTDS) system so that requirements of users for ever-increasing digital dynamic model simulator software in the electric power system can be met.