In order to research spark discharge, including the energy, electromagnetic radiation characteristics and its influence on surroundings, a spark discharge experiment was set up, voltage waveforms were recorded by an oscillograph and discharge energy was calculated when discharging. Physical models were founded using FEKO and different electromagnetic radiation patterns were simulated under a range of frequencies. When frequency is low, the radiation pattern is similar to dipole model; when frequency is high, the pattern is mainly on the upper side of electrode level. In the range of 700~900 MHz, electromagnetic radiation hazard of spark discharge is relatively serious.