Biomass gasification based building cooling, heating, and power (BCHP) system is an effective way of increasing and improving the use of biomass resources and distributed generation. The key step in designing a BCHP plant is to determine the best configuration in terms of the integrated performance from energy, economic and environment. This paper analyzes the configuration and operation strategy of the biomass gasification based BCHP system and proposes an integrated optimization design model combined a case study in Harbin, China. The configuration of the biomass BCHP system with thermal storage unit and hybrid cooling system is optimized to minimize the annual total cost (ATC) by the genetic algorithm (GA). Then, the energetic, economic, and environmental performances of the BCHP system are compared to the separation production (SP) system. The optimal results for the case study indicate that the optimal biomass gasification based BCHP system saves 45.4% ATC and reduces 90.4% CO2 emission than the SP system. Finally, the contour-surfaces of ATC changed with the capacity configuration are obtained, and the validation and error analysis of the optimization model are verified. The results show that the error of the optimization ATC is only 0.00041% and the optimization speed of this optimization model is 12.4 times than that of the general cycle calculation. (C) 2014 Elsevier Ltd. All rights reserved.