During the operation of Direct Current (DC) transmission, transient electric shock significantly impacts the work and lives of both line workers and nearby residents. This paper presents a numerical calculation method for studying transient electric shocks, which can investigate the electrical parameters during transient electric shock processes and the changes in the electrical effects on different parts of the human body at the moment of shock. Firstly, a transient electric shock circuit model and a simplified three-dimensional finite element human body model containing typical organ tissues were constructed according to the specific scenarios of transient electric shocks. The induced voltage on the human body, discharge current, and surface current density distribution on the human body were calculated. The results indicate that in extreme transient electric shock situations such as a human barefoot touching the metal frame of an umbrella under transmission lines, minimal stimulation is experienced by the right hand, head, and toes. The left hand and left leg receive strong initial stimulation, which quickly diminishes. However, organs in the chest and abdomen, especially the heart, stomach, and lungs, experience slower current decay, leading to continuous current stimulation. The method can investigate both the macro mechanisms of transient electric shocks and the micro effects of electric fields on the human body during the occurrence of transient electric shocks, which holds practical value and serves as a reference for in-depth research on transient electric shocks.