The invention discloses a two-port testing method of an alternating current milliohm meter, which is used for measuring the resistance and comprises the following steps: firstly, one end of a coaxial-cable is connected with an excitation source circuit, a shielding layer of the coaxial-cable is connected with an earth wire of the excitation source circuit; secondly, one end of the other coaxial-cable is connected with a sampling circuit, a shielding layer of the coaxial-cable is connected with the negative terminal input of the sampling circuit, an inner core wire of the coaxial-cable is connected with the positive terminal input of the sampling circuit; thirdly, the other ends of the two coaxial-cables are respectively connected with two ends of a tested piece; fourthly, excitation current flows through inner cores of the coaxial-cables and then flows through the tested piece, at last flows back to an excitation source through the shielding layers of the coaxial-cables; fifthly, current of the sampling circuit flows through the inner cores of the coaxial-cables, and then flows through the tested piece, at last flows back to the sampling circuit through the shielding layers of the coaxial-cables. The invention reduces the area of the excitation circuit and the sampling circuit, effectively lowers the noise coupling, inhibits the magnetic field coupling interference, obviously improves the interference free performance, and increases the testing accuracy.