Abstract. Based on metal oxide gas sensors and DSP technology an odor compass is designed in this paper. Odor compass estimates direction of point odor source by analyzing responses of sensors which are placed on different concentration gradient. Main structure consists of distributed metal oxide gas sensors and plexiglas material. Signal sampling and processing are accomplished by DSP system. The directivity of whole system is tested in uniform wind field. Experimental result shows that the responses for the odor sources with 30°disparity have obvious difference. Ratio of resistance response is selected as characteristic quantity. In this way, influence which is generated from individual difference of sensors is effectively eliminated.