As one of promising clean coal technologies used to reduce pollutant emission and CO2 discharge, co-gasification has been extensively investigated. In this paper, a new co-gasification technology using coal and natural gas was developed. The distinct advantages of this technology are the excellent fuel flexibility and the availability to establish the gasifier by reconstructing the blast furnace or similar shaft furnace. Based on the concept of the new co-gasification technology, lab-scale experiments and modeling study were carried out. The obtained results indicate that gasification is undertaken at ideal thermodynamic environment where quasi-equilibrium could be reached without catalysts. The modeling results are in agreement with experimental data, demonstrating the validity of the model and that Aspen Plus is a useful tool for the analysis of the co-gasification process. Furthermore, the effect of major operation parameters, including oxygen flow rate and steam flow rate, on co-gasification process was investigated using the developed model.