With the encouragement of LNG (liquefied natural gas) application in China, CCHP (combined cooling heating and power) system fueled by natural gas has been receiving increasing attention. This paper presents optimization of CCHP system on their design and operation from energetic analysis, economic operation and environment effect viewpoints. CCHP system for hotels, offices and residential buildings in Dalian (China) is given to ascertain the effectiveness of the model. Weighting method and fuzzy optimum selection theory are employed to evaluate the integrated performances of CCHP systems with various operation strategies. Results show that: (1) Hotels have the greatest contribution (42.28%) to the energy savings based on energetic analysis sub-model because of their relatively stable electricity loads. (2) CCHP systems reduce the annual total costs for all operation cases compared with the reference system for hotels and offices. However, CCHP system achieves no economic merits for residential buildings. (3) The applications of the CCHP system decrease pollutant emissions in all operation cases for the studied buildings. (4) CCHP system driven by gas engine has better performance than driven by gas turbine. Coupled with renewable energy sources and with thermal storage tank are mostly optimum operation cases from energetic, economic and environment criteria. (C) 2016 Elsevier Ltd. All rights reserved.