Studying of the dynamic behavior of the rolling ship on sea waves is one of topics of special interest due to its close association with the ship stability and its direct impact on the efficiency of the work of some of the systems and processes inside the hull. This paper includes an explanation of the proposed mathematical model to study the dynamic behavior of the rolling ship on irregular waves in order to calculate the curves as a function of ship breadth at different values of ship speed, bearing angle and metacenter high, and thus determine the ship speed and bearing angle that causing resonance at defined value of metacenter high. In addition to determine the critical breadth coincide with the design speed of the ship. A computer program was prepared to perform calculations according to the proposed model, which allowed studying the effect of some parameters of the investment of the vessel (ship speed, and the angle of its route for the main direction of spread of the waves) on ship rolling. It had been reached through this research to extract mathematical equations which allow a precise and clear explanation of the dynamic behavior of the ship rolling on waves.