So far, Maisotsenko cycle has been applied to many fields such as heating ventilation and air-conditioning, power industry, chemical production, and so on. A lot of researches about classical thermodynamic analyses of Maisotsenko cycle have been made. A new cycle model of combined Diesel and Maisotsenko cycles considering heat transfer loss (HTL), piston friction loss (PFL) and internal irreversible loss (IIL) was proposed in this paper. By using the finite time thermodynamic (FTT) theory, the power and efficiency performances of the Maisotsenko-Diesel cycle (MDC) were studied. Effects of mass flow rate (MFR) of water injection in the Maisotsenko air saturator (MAS) and the other parameters related to the design of Diesel engine on the optimal cycle performances were analyzed. Furthermore, it was testified that irreversible MDC was superior than conventional irreversible Diesel cycle in both power output and thermal efficiency. The results can expand the application of Maisotsenko cycle (M-cycle) and provide some theoretical guidelines for the practical devices.