The construction and use of high-voltage AC power transmission and transformation projects is increasing. This has led to a rise in human transient electric shock phenomena near the line, which is causing great inconvenience to both line staff and nearby residents. This paper introduces a numerical calculation method and model for studying transient electric shocks in humans under AC transmission lines. The model includes a circuit and finite element biomimetic human body models. It focuses on extreme scenarios of transient electric shocks. Induced voltages and currents are calculated using the established circuit model, and then changes in surface current density are computed by the finite element human body model. Experimental simulations validate the model and method. The study also investigates changes in surface current density when shocks occur at the top of the human’s head. Results show that the circuit model captures macroscopic mechanisms and parameters of transient electric shocks, while the finite element human body model offers a microscopic perspective on their electrical effects. During shocks, the legs exhibit relatively higher current density in the two current paths from the left hand to the feet and from the head to the feet. The chest and abdomen receive a stronger current stimulus when an electric shock occurs at the left-hand end. The research findings can provide a reference for the electromagnetic environment assessment of AC transmission lines.