The invention discloses a method for eliminating ambient level in the electromagnetic radiation emission automatic test, which adopts the field superposition principle and a dipole antenna radiation model, collects the correlative quantities of two test points of different distances and utilizes an ambient level elimination module to analyze the far field or near field condition, to find the approximate solution of the radiation emission at the first test point A of a sample. The instruments demanded by the electromagnetic radiation emission automatic comprise a receiving antenna, a EMI receiver and a PC, wherein the receiving antenna is connected with the input interface of the EMI receiver, the PC is connected with the control interface of the EMI receiver and contains an ambient level elimination module composed of a near-far field judgment unit, a far field analysis unit and a near field analysis unit. The method can extract the radiation emission of a sample from the test result under a complex electromagnetic condition, to effectively eliminate the effect of the background ambient level on the test result under a non-standard test condition.