The increasing interests in climate change heighten the need for an agro-economic model to analyse climate change impacts on farmers’ incomes. Many researchers have turned to crop yield response models to estimate farmers’ yield and income loss. A classic method used by economists to establish yield response models is to build up the statistic relationship between historical yield changes and climate change through regression models. However, without comprehensive experimental data from each region such as crop yields response to CO2 concentration, these crop-yield response models may provide misleading predications. An alternative approach is the use of crop biophysical simulation models. Based one biophysical model Agricultural production systems simulator (APSIM), we develope an agro-economic model, WATER-BIOMASS DYNAMI, to simulate the change of crop yields and farmers' income affected by varied climate change scenarios and other economic factors. We used the WATER-BIOMASS DYNAMIC model to analyse the agricultural economic impacts of four climate change scenarios in the Australian Wagga Wagga wheat production area.