A computing method for hub ultimate strength of a wind turbine generator system belongs to the technical field of wind power generation, and comprises the following steps: modeling by adopting software of finite element analysis, performing finite element mesh generation, setting constraint conditions and computing to obtain a deformation and stress cloud chart. The modeling process is as follows: 1, drawing a 3D model for a hub, importing the 3D model into a finite element software platform, and drawing a 3D entity model for the connection part of blades and the hub and the connection part of a main shaft and the hub in the finite element software; 2, setting material attributes for the blades, the main shaft and the hub, establishing a finite element model thereof, rigidly coupling the blades, the main shaft and the hub, and determining an overall coordinate system of the hub; 3, establishing nodes at root parts of the hub and each blade, converting the nodes into a blade root coordinate system specified by Germanischer Lloyd, then rigidly coupling the nodes to the blades, so that the load can be transmitted to the hub through the blades. The computing method facilitates accurate computation of strength performance of the hub, saves the computing time and improves the computing efficiency.