In this paper, optimization and techno-economic evaluation of a Combined Cooling, Heating and Power ( CCHP ) system for a hotel in Kerman has been investigated. The design parameters of system includes capacity of gas engine (as prime mover), partial load (PL), thermal capacity of boiler, the cooling capacities of electric and absorption chillers that by using energy, economic, and environment analysis and relative annual benefit (AP), as objective function, have been optimized. Then for optimum results the payback period (PB) has been investigated, by considering the time value of money and without it. Results show increase of number prime mover, reduce the annual benefit and this process has reverse relation with classic payback period since choosing a 2550 kW gas engine, maximum relative annual benefit (AP) with value of 45.5×105 ($/year) and minimum payback period (PB) of 6 years obtains. Also when the costs of energy increases and one prime mover (PM) is selected, the results of traditional and classical payback method are different as the time of payback period increase in classic method and decrease for traditional method.