Abstract: To reduce the effect of EUT on the measurement of environment E-field intensity and to improve the measurement accuracy of electromagnetic radiation susceptibility test, a method was proposed by combining electromagnetic field numerical calculation with experimental verification. A cube electrical conductor was taken as EUT model to study the change laws of E-field distribution effected by EUT in uniform electrical field environment or electromagnetic reverberation chamber. Taking the environment E-field intensity before the EUT placed as reference, the relative error caused by electric field distortion in typical direction was determined, and the curve of the measurement error varying with the distance to the EUT was presented. It is concluded that the relative measurement error of environment E-field intensity is less on the diagonal line of EUT front surface,the error can be decreased to ±10% or less when the distance is greater than the wavelength λ. As for the low frequency measurement, while the distance is in the interval of(0.15~0.25)λ, the measurement error can be decreased to 15%, which can meet the test error requirements. When the EUT is put into the reverberation chamber, the E-field distortion mainly affects the mean E-field intensity distribution near its surface, as long as the distance to the surface of EUT is greater than 0.4λ, the measurement error caused by E-field distortion can be decreased to 2 dB, when the distance to the surface of EUT is in the interval of(0.5~0.9)λ, the relative error of E-field is smaller, it is best to measure the environment E-field intensity in this interval.