The fault data of ships′ mechanical system are usually not well recorded during operation and maintenance activities, and are typically incomplete and inaccurate. For such incomplete data, fault trend was justified by graphical representation. On this basis, historical fault data was analyzed using homogeneous Poisson process, non-homogeneous Poisson process and geometric process respectively. Numerical results show that the fault of geometric process is minimized, and the future fault intensity can be predicted.