Abstract: Disclosed is a method for detecting and identifying toxic and harmful gases based on machine olfactory. Information about the toxic and harmful gases is firstly collected through the machine olfactory system and then analyzed through a Selected Linear Discriminate Analysis (SLDA) combined with a Markov two-dimensional distance discriminant method to identify various toxic and harmful gases. The algorithm disclosed in the invention extracts the characteristic information of the sample data, and then fast processes and identifies the information as a linear recognition algorithm does, having wide applications in the field of machine olfaction, especially in detecting and identifying the toxic and harmful gases in real-time based on machine olfaction. The algorithm involves low complexity and high recognition efficiency.