By using a two-dimensional, time-dependent electromagnetic field model (EM model), the spherics and red sprite phenomenon is studied. The simulation results show that the total electric fields produced by lightning include radiation field and quasi-electrostatic field (QEF). The spherics result from the radiation field, which propagates within the earth-ionosphere waveguide. The optical emissions of the first positive band of N2 caused by the QEF form the red sprite phenomenon. By means of simulation we have found the red sprite apparently appearing in “V” shape during its evolution and a bright nucleus existing within the structure of the red sprite, while the brightness of the exterior of the red sprite, which is referred to as sprite halo, being relatively weaker.