A CHP-HP integrated system coupled by combined heating and power system and heat pump has been proposed previously, but its performance varies with the design and operation strategies. This paper develops a multi-objective optimal model of the new integrated system based on the comprehensive indicators, i.e. primary energy saving ratio, CO2 emission reduction ratio and annual expense saving ratio. The key design parameters, such as the prime mover capacity (PM), the outlet temperature from heat pump and the decision value to run the PM, are optimized by genetic algorithm. In order to verify the multi-objective optimal model, a case analysis is presented. The results show that the comprehensive performance of 26.8% is the best when the PM capacity is selected as 1136 kW, the decision value is set as 0.6 and the outlet temperature from heat pump is set as 25. Moreover, a sensitivity analysis is implemented to identify how the system performance changes regarding the variation of key design parameters. Finally, it is concluded that the multi-objective optimal model is very helpful for the optimization design and practical applications of the CHP-HP integrated system. (C) 2017 Elsevier Ltd. All rights reserved.