The invention discloses a method for improving sensitivity of magnetic liquid micro differential pressure sensor. Devices utilized in the method include a left arm coil (1-1), a right arm coil (1-2), magnetic liquid, a U-shaped organic glass tube (3), a rubber plug (4), a pressure meter (5), a first slide rheostat (R1), a second slide rheostat (R2), an alternating current power source (U) and a voltmeter (V). The magnetic liquid (2-2) is injected into the U-shaped tube, and then the magnetic liquid (2-1) is injected into the U-shaped tube; and interface of the two magnetic liquid is in the middle of the coils. The rubber plug is stuffed; and a lateral opening end of the left arm of the U-shaped tube is connected with a pressure source and the pressure meter through a tee joint. The two coils are respectively connected with the slide rheostat (R1) and the slide rheostat (R2) in series and then connected in parallel at two ends of the alternating current power source (U) to form a bridge circuit. Under the same pressure, differential capacity of the magnetic liquid micro differential pressure sensor adopting the method is more remarkable; the sensitivity of the sensor is remarkably improved compared with that with a single high-intensity magnetic liquid (2-2); and cost is saved.