The problems about extracting cleaning signals in the heavy noise and its hardware implementation were discussed. The Butterworth filter was proposed to distinguish the vibration noise and the grain signals. The lowest order of filter to meet performance was determined according to its transition region width and stop-band attenuation. An 8-order Butterworth filter used VCVS topology structure as basic units was constructed by class-bind method. Analogue simulation of the high order filter was proceeding on EWB and refining test was proceeding on the combine. Experimental results was well coincided with simulation results and showed good filtering property in extracting grain signals in the heavy noise of combine.