Deep level transient spectroscopy (DLTS)was applied successfully to characterize the electric properties of self organized InAs quantum dots.The energy of the ground state of 2.5 ML InAs quantum dots was obtained at about 0.13eV below the bottom of the conduction band of bulk GaAs,and there occurred the lattice relaxation associated with the change of charge state of quantum dots.The corresponding capture barrier energy of such dots for electrons is about 0.32eV.This work shows that the electric characteristics of quantum dots behave somewhat like deep centers and can be investigated by using deep level investigation methods.