Abstract: In this paper, the model of resistor-aided broadband equalizers was provided and the equivalent circuit was analyzed. Different from traditional analytic method, this paper provided the method to calculate the resonating frequency、 bandwidth and attenuation quantitatively. The formula for calculation and the steps to design broadband equalizer were offered in detail and a microstrip equalizer was designed according to this. The measure results showed good performance. Addition ally, a tunable broadband coaxial equalizer was designed. By tuning the length of coaxial resonator and the length of the re sistor ring, the equalizer can be frequency、Q factor and attenuation adjusted after the equalizer had been made. This equaliz er was small in size and would be applied widely.