To ensure a more uniform microstructure distribution of forging and improve the service performance of aeroengine disk parts, an automated preform design method is proposed for integrated preform shape design and optimization based on the NURBS curve, finite element method (FEM), and genetic algorithm (GA). Firstly, the random preform shape graph is automatically constructed by the NURBS curve design criterion. The volume and shape complexity are used as the constraints of the preform. Then the ratio of the mesh area within the set strain range to the total mesh area is used as the fitness function for the uniformity of deformation, and the genetic algorithm module is used for optimization. Finally, a large disk forging is an example of its optimal design. The results show that the deformation uniformity of the forgings is excellent, its fitness value is as high as 99.59%, and there are no problems such as folding, underfilling, and limited distribution of flash, which verifies the effectiveness of the method. In addition, the method has the advantage of strong universality, which can find the preform shape with good deformation uniformity for any shape forgings.