A framework is proposed for sustainability study of coal based chemical and energy processes. Comprehensive analysis from efficiency, energy, economic, and environment perspectives. Process modelling, synthesis, and life cycle analysis, are conducted. Based on these multi-layer analyses, optimization is applied to explore for new process innovation and existing process modification. The analysis is illustrated with two case studies. The first case is the coal based methanol production process, which environmental impacts were investigated in a life cycle assessment. The second case is the co-production of electricity and methanol, in which key parameters are designed by mutual optimisation of energy efficiency and economic cost.