The invention provides a finite element numerical simulation and parameter analysis method for fatigue of a metal material after corrosion, which comprises the following steps of: scanning an existing corroded metal material test piece to obtain a corrosion three-dimensional digital model, and establishing a three-dimensional coordinate database of corrosion morphology; establishing a random probability model, randomly selecting three-dimensional coordinate points, recombining point clouds, fitting a new corrosion surface, and establishing a new corrosion model; extracting two corrosion surfaces of the obtained new corrosion model, utilizing Hypermesh software to carry out grid division and establishment of a hexahedral grid model, and then combining ABAQUS software and Fe-safe software to carry out fatigue calculation on the corrosion model. By the adoption of the technical scheme, the problems that corrosion and fatigue tests are long in consumed time and large in test result discreteness are effectively solved, time is effectively saved through the finite element fatigue calculation method, and compared with the test result, the fatigue simulation result is accurate and effective.