(BEDT-TTF)[FeBr4] single crystal is grown with electrochemical crystallization method, and its crystal structure is determined by four-circle single crystal diffraction. From 300 K to 185 K, the crystal resistivity is related to the efficiency of electronic thermal excitation and the strength of the electron scattering by ionized impurities, while from 185 K to 10 K, the conductivity depends mainly on the ionization of the impurities and defects in crystal. Because of electron scattering increased by the effect of Lorentz force, the magnetic reluctance has positive value. The magnetism of the crystal is determined mainly by magnetic ferric ions, and neither ferrromagnetic coupling nor antiferromagnetic coupling between the ferric ions in crystalis induced. The resonance signals of the electrons and the d electrons are found in the electron paramagnetic resonance spectra, and the -d coupling is enhanced as the temperature is decreased. When the crystal rotates along different axes, the resonance signal changed with the angle of rotation, is greatly different.