The invention discloses a balanced variable filter, which comprises a first half-wavelength microwave transmission line, a second half-wavelength microwave transmission line and six variable capacitors, wherein the first half-wavelength microwave transmission line and the second half-wavelength microwave transmission line are in bilateral symmetry, the first variable capacitor, the second variable capacitor, the third variable capacitor and the fourth variable capacitor are the same in type and parameters, the fifth variable capacitor and the sixth variable capacitor are the same in type and parameters, each half-wavelength transmission line is in vertical symmetry, first ends of the first variable capacitor, the second variable capacitor, the third variable capacitor and the fourth variable capacitor are connected with four terminal points of the first half-wavelength microwave transmission line and the second half-wavelength microwave transmission line respectively, first ends of the fifth variable capacitor and the sixth variable capacitor are connected with middle points of the first half-wavelength microwave transmission line and the second half-wavelength microwave transmission line, second ends of the six variable capacitors are respectively grounded. By the aid of the technical scheme, the differential passband frequency of the balanced variable filter can be regulated by controlling capacitance values of the variable capacitors loaded in the terminal points; and high common-mode rejection degree of the balanced variable filter can be kept stable within the variable range of the differential passband frequency by regulating the capacitance values of the variable capacitors loaded in the middle points.