In order to study the dynamic response and stability of transmission tower foundations in karst geological regions under earthquake action, the finite element numerical simulation method was used to study the changes in acceleration response, settlement, stress, and damage levels of transmission tower foundations under different spectral characteristics of seismic waves, peak acceleration of seismic waves, sizes of karst caves, and different vertical distances from the transmission tower foundations. The results show that the acceleration response of the top of the transmission tower foundation under earthquake actions has a significant amplification effect; With the increase of peak acceleration, the settlement value of the transmission tower foundation continues to increase; With the increase of the diameter of the karst cave, the change trend of the foundation settlement conforms to the exponential function distribution; The influence of karst caves on the settlement of the transmission tower foundations decreases with the increase of distance and the settlement fluctuation amplitude is related to the vertical distance between the karst cave and the transmission tower foundation; There is stress concentration at the intersection of the corner of the transmission tower foundation and it is a vulnerable area to earthquake damage. When the vertical distance between the karst cave and the tower foundation is greater than 3 meters, the inclination is less than 5‰ , which meets the settlement limit requirement. However, when the vertical distance between the karst cave and the tower foundation is less than 3 meters, instability is prone to occur. In practical engineering design, attention should be paid to and prevention measure should be taken. The research results can provide reference for the stability assessment of tower foundations under earthquake action, as well as for their seismic design, construction, and maintenance.