The invention relates to a characteristic impedance matching method in cable transmission attenuation characteristic test, comprising the following steps: a signal generator capable of outputting a variable-frequency sinusoidal voltage signal is connected to the head end of a cable, a non-inductive adjustable resistor is connected in series between a conductor wire core and a metal sleeve at the tail end of the cable, and a signal output end and a voltage signal of the non-inductive adjustable resistor are connected to a measurement device; the signal generator inputs sinusoidal voltage waves of different frequencies in turn, an oscilloscope is used to measure the voltage signal of the non-inductive adjustable resistor and the tail-end voltage wave amplitude under the sinusoidal voltage wave of each frequency, and the non-inductive resistance value is recorded when the change of the amplitude of tail-end voltage waves and the peak of input sinusoidal voltage waves is within +/-3%; and a linear regression analysis is made of the non-inductive resistance values under different frequencies, singular points are eliminated, and the tail-end matching impedance is obtained. Through the method, the characteristic impedance value of a coiled cable at high frequency can be measured accurately, and the test accuracy is improved.