Abstarct: current study, a cogeneration system of power, cooling and heating was examined from the perspective of the first and second law of thermodynamics and economically. In this study, the objective is to improve the efficiency of the ejector compression refrigeration cycle and, subsequently, to improve the overall system efficiency. The system consists of a micro gas turbine, an organic Rankin cycle combination with an ejector cooling cycle, a domestic hot water heat exchanger and an open loop ground water exchanger (well water). The numerical calculations of the present work are done using EES software. The evaluation parameters included the output pressure of the main pump of the Rankin cycle, Groundwater temperature, fluid mass flow rate of combined cooling and power cycle, Mass flow rate of the fluid passing through the expander of combined cooling and power cycle And the evaporator's working temperature. Among the above parameters, the mass flow rate of combined cooling and power cycle and the mass flow rate of the fluid passing through the expander of the combined cooling and power cycle have a greater impact on the energy and exergy efficiency of the system. Also, the effect of using R123, R141b, R245fa and R1234ze working fluids and the above parameters were observed on energy and exergy efficiency of combined power and cooling cycle and overall system. Also, the impact of system production on break even point, net present value, internal rate of return has been evaluated. The results show that the R123, R141b, R245fa, and R1234ze working fluid yield 51.04%, 53.23%, 50.71% and 47.97% overall energy efficiency, and 53.4%, 54.51%, 51.88% and 48.49%, overall exergy efficiency respectively. The thermodynamic and economical results show that fluids R141b and R123 are the most suitable fluids among the studied fluids.