This thesis developed a practical methodological framework, which integrated the bio-physical and socio-economic processes within the food system across different scales. The framework provides a useful tool for the assessment of food security and possible adaptation related to climate change. It was applied in China, a country with rapid economic growth and a large population, in order to evaluate multiple dimensions of food security related to climate change and socio-economic development in the future. In the framework, an improved bio-physical crop model was coupled with an improved food economic model by scaling up from the farm level to the national level. The bio-physical crop model was developed from the site-based Decision Support System for Agrotechnology Transfer (DSSAT) model in order to investigate the impacts of climate change on physical production of a crop only related to environmental factors. The food economic model was developed from a partial equilibrium economic model, China's Agricultural Policy Simulation Model (CAPSiM). This was done in order to simulate the response of a socio-economic system to the negative consequences on a food economic system from the bio-physical change in crop production due to climate change. Case studies of China and the Jilin province were investigated by applying the framework. The impacts of climate change on yield and phenology of maize under multiple greenhouse gas emission scenarios were studied at provincial and national levels in three time periods, 2020s, 2050s, 2070s, using the improved bio-physical crop model. In general, maize yield reduction due to climate change ranges from -3% in 2020 to -14% in 2070. The worst yield is -20.5% in 2070 produced under the A1FI scenario. Food security for China until 2050 was projected under multiple climate change and socio-economic scenarios by using the food economic model, and analyzed with respect to food availability, food price and the system resilience to sudden disasters. Modelled climate change impacts on food availability in this study are minimal, producing only a 23 Mt (~8%) gap between supply and demand for maize by 2050. The socio-economic system will compensate for the impacts of climate change on the self-sufficiency of grains by about 8% of total production for the whole country. The impacts on single grain would cause the prices of other grains to rise in future. The effectiveness of potential adaptation measures was assessed quantitatively at both farm and national levels. Uncertainties among different scenarios are discussed for China and the Jilin province.