Abstract: Considerable interest has recently arisen in the use of arrays of gas sensors together with an associated pattern recognition technique to identify the odours given out from food. The performance of the pattern recognition technique depends upon the choice of parametric expression used to define the array output. At present, there is no generally agreed choice of this parameter for either individual sensors or array of sensors. In this paper, feature parameter (FP) on experimental data gathered from the response of eight tin oxide gas sensors was used to identify two types of vinegar. And the technique of organizing feature parameter (OFP) based on formulae expression tree by using genetic algorithms was applied to parametric data. Then the optimum FP to distinguish different odours can be used sensitively. It could solve the problem on how to get optimum feature parameters, and make the genetic algorithm more convenient and straight. The formulae expression tree for the fusion of feature parameters was discussed and then the selection, cross over and mutation for the genetic algorithm were studied. The result showed that the new method is useful and effective for odour recognition.