Abstract: A kind of new sensor of simple structure, easy manufacture and good performance,IDC structure with polyanline film has been studied, the gas-sensitive characteristics of polyanline film have been tested and the response and comeback curves of current conductance for different SO₂ contents have been obtained. A forecasting model of BP neural network starting from gas-sensitive characteristics of polyanline film with the curve of response current conductance as input nodes of network and the corresponding SO₂ concentration as the output of the network has been advanced. By means of the network the four group data have been tested.The results show that the model possess good forecast characteristics with errors smaller than 3％ . This method is different from traditional calibration, the latter requires stable detection for 4 min, while neural network signal pattern detection does not necessarily require a steady response. And as a result, the response time can be greatly reduced (shortened by 75％).