Abstract: This paper analyzes the model structure of small-scale unmanned helicopter’s yaw channel.The parameter transfer function model using the alterable fractional form is established.Subsequently,a genetic algorithm(GA) based method is designed to identify the established model structure,and the system model structure and the parameters can be obtained simultaneously.Based on safety and convenience,a kind of ground stand is produced,and the experimental data used for identification and validation is collected and pre-treated.The results are used to explain the feasibility of the proposed identification algorithm.