With the decline of hardware device price and the development of image recognition analysis technology, face recognition technology has been widely used in various industries. As an important part of face recognition, face alignment bridges the two important steps of face detection and feature extraction, and plays the role of the top and bottom. Relevant research results show that if face alignment is effective, face recognition performance is effectively improved, and vice versa. Most of the traditional face alignment methods use two-dimensional faces for alignment, and two-dimensional face pictures usually cannot represent the change of face depth, which leads to the problem of inconsistent shape when the face is rotated in three-dimensional space. Because faces are usually rotatable in three dimensions, the use of two-dimensional alignment methods is prone to large errors. To this end, this paper proposes a 3D face alignment method based on convolutional neural networks. The method uses the end-to-end idea to complete the face alignment by inputting only one pair of face images and using the PRN (Position Map Regression Network) structure to locate the key points of the face, so as to obtain the 3D information of the face. In order to further optimize the network model parameters, the same weight ratio of the face area not is set and the loss function is improved.