To overcome the problem of film-forming technology, water-soluble polypyrrole was obtained in the process of chemical oxide by adding a small amount of poly (sodium-p-styrenesulfonate). The resulting product PPy/Poly(sodium-p-styrene sulfonat) was coated on the interdigital electrodes of carbon via spin-coating or casting approach, and its gas-sensitivity to trimethylamine at room temperature was investigated. The results indicated that, the technology of film-forming was not only improved greatly, but also this film still showed good gas-sensitivity to trimethylamine of 3.189 x 10(-1) mol/m(3), its value of gas-sensitivity had reached to 2-3 orders of magnitude within 3 min, had good selectivity to analogy gases, and its resistance to moisture was improved obviously. Otherwise, this film also exhibited good reproducibility and stability, and easily recovered with high-purity N-2 at room temperature.