This paper studies the passenger demand of air-rail intermodal transport from the perspective of travel utility. Combined with prospect theory and regret theory, it proposes basic utility, risk perception utility and gratification utility. Based on the converted gravity model, the utility function is optimized, and the passenger demand forecasting model of hinterland city-HSR-flight is obtained. Taking Nanjing Lukou International Airport as the target airport, it studies the passenger demand of air rail intermodal transportation by integrating the airports with passenger throughput greater than 10 million, the nearest ten airports and all airports in Jiangsu Province according to the administrative division. Based on Wilson model, the prediction accuracy of air rail combined transport radiation radius is improved, and the relationship between annual per capita travel times and per capita GDP of hinterland cities is constructed, and the passenger demand of air rail combined transportation in hinterland cities is obtained. Finally, according to the passenger travel utility evaluation, the air rail intermodal passenger flow distribution is carried out to accurately identify the demand for the airport.