The invention discloses a squaraine-polymer-based ammonium/nitrogen monoxide two-component sensor, as well as a preparation method and application thereof. A preparation manner and condition for the sensor are optimized. The squaraine polymer containing azo functional group based ammonium/nitrogen monoxide two-component sensor comprises an interdigital electrode and a coating material with which the interdigital electrode is coated. The coating material is a squaraine polymer containing azo functional group and has high sensing selectivity for ammonium and nitrogen monoxide, the minimum limit of detection thereof is 1 ppb and the response/reversion time is 82s/185s. The sensing performance of the sensor for nitrogen monoxide is also tested, the minimum limit of detection can reach 40 ppb and the response/reversion time is 112s/921s.