A new reflectionless filter with discharging circuit is presented. Under the premise of keeping the original filter unchanged, a discharging circuit is added. The relationship between the passband and stopband of the discharging circuit and the original filter is similar to the duality of the circuit. Without affecting the performance of the original filter, the reflected energy of the original filter is discharged to the ground through discharging circuit, so as to achieve no reflection of the filter, avoiding the interference to the input. Analytical design equations are provided so that the reflectionless filter can be designed. According to this design method, the reflectionless dual-band bandpass filter is designed and fabricated. Simulation and measurement results are in agreement. It has good reflectionless performance. The feasibility of the design method is verified.