Stirling Engines are power machines that operate over a closed, regenerative thermodynamic cycle with the ability to use any source of heat including solar energy. In order to study further the promising β type Stirling engine with rhombic drive mechanism, there is a need of an analytical thermodynamic model which could be used in a dynamic analysis for preliminary design. In thi s study, a combined dynamic and thermodynamic model for β type Stirling engine is developed. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. To aim at more real istic values, the model have to take into account the heat losses and irreversibilities on the engine. Numerical simulation is performed and the effects of the regenerator effectiveness and dead volumes are studied. Furthermore, the network and the thermal efficiency of the engine is obtained under different geometrical conditions. Effects of the effectiveness of mechanism, the dead volume ratio, and the regenerator effectiveness on the maximum network of the engine are evaluated. Results show that energy efficiency decreases with increasing dead volume and decreasing regenerator effectiveness. As a conclusion, a handy and accurate model is developed and can be used as a preliminary design principle of β type Stirling engine.