Abstract: From the black-box system identification and the dynamic system prediction theories, a black-box analytic method of gas field dynamics is presented. In this method, the gas field is taken as a black-box dynamic system. The gas production or cumulative gas production and the well head flowing pressure are considered as the system input and output respectively. Practical models have been established by usingr the system identification technique to identify four linear models. Two dynamic system prediction models have been used to predict the gas field dynamics. With its simple model structure, the method is easy of operation and widely applicable, and its softwares are good for common use in the gas field. The method is particularly useful in gas fields with fractures and abnormed formation pressure.