The application of mathematical theory in engineering is crucial to solve complex challanges nowadays. The insights of recent mathematics development are great momentum to utilize the mathematics into the different fields in education, engineering, and business. In maritime transportation, fuel efficiency plays a vital role in creating efficient operation measures. The concept of optimization theory, along with the least square error method in mathematical theory, has been used to solve this issue. To partly contribute to this topic, a mathematics model has been established based on the least square error theory to accurately estimate the fuel consumption mass of marine diesel engines. In this model, the complexity of uncertain factors impacting the fuel consumption of marine diesel engines is addressed to accurately improve the fuel consumption estimation model. Based on the least square error method, a reduction in fuel consumption estimation error is achieved. A full evaluation of this model will be presented through the performance metric, including the coefficient of determination (R²), the mean absolute error (MAE), and the root mean square error (RMSE). This study is significant in determining the fuel consumption of marine diesel engines nowadays through mathematical theory. In the future, an advanced model will be established from this mathematical model to determine fuel efficiency in maritime transportation.