One of the most important achievements of the Carnot was creating a limit for heat engines; this limitation is a criterion for measuring and comparing the performance of heat engines. Classical thermodynamics studies completely the equilibrium and reversible processes but transfer phenomena effects have been ignored, while in the real irreversible process, there are finite time processes and finite size systems. On the other hand, the close relationship between thermodynamics, fluid mechanic and heat transfer has caused thermodynamics to move from theoretical analysis toward a comprehensive and real analysis. Another point is that all the practical processes are irreversible. This study analyzed the irreversible combined cycle in finite time thermodynamics. The combined cycle studied consists two endoreversible cycles and three thermal sources. The irreversibility has occurred between the subsystems and the thermal sources and sink on the system boundaries. By solving algebraic equations, obtained dimensionless total power and efficiency were calculated based on dimensionless variables. The MATLAB programming code is used to solve algebraic equations. Finally, it is obtained that the thermal efficiency and dimensionless total power functions of the heat sources temperature, working fluid temperature and thermal conductance. Also, the effects of each dimensionless variable were investigated to the proportion of dimensionless total power and efficiency. In this study, the parameter study has been used for improving the irreversible combined cycle in the finite time thermodynamics. In addition, Optimization results have shown that the maximum dimensionless total power and thermal efficiency associated with it are 0.086102 and 47.81%, respectively.