We analyzed the effect of tall buildings on the lightning return-stroke electromagnetic fields by using finite-difference time-domain (FDTD) technique.Results show that tall buildings have obvious effect on the return-stroke electric fields and weak effect on magnetic fields(less than 10% when the building is 50 m high).The electric field at the top of buildings is closely related with the building height,and the vertical/horizontal component of the electric field gradually increases/decreases with the increase of building height.When the building is high as 20 m,50 m,and 100 m,the vertical electric field at the building top is 1.3,1.7,and 2 times of that at the ground level,respectively,while the horizontal one is 0.9,0.8,and 0.7 times,respectively.We also analyzed the factors influencing the electric fields near tall buildings.The ground level horizontal electric field is obviously affected by the ground surface finite conductivity,the greater the soil conductivity,the faster the negative amplitude decays.While the horizontal electric field above the ground is affected by the buildings as well as the observation point location.