Decoding visual information from human brain activity has seen remarkable advancements in recent research. However, due to the significant variability in cortical parcellation and cognition patterns across subjects, current approaches personalized deep models for each subject, constraining the practicality of this technology in real-world contexts. To tackle the challenges, we introduce Wills Aligner, a robust multi-subject brain representation learner. Our Wills Aligner initially aligns different subjects' brains at the anatomical level. Subsequently, it incorporates a mixture of brain experts to learn individual cognition patterns. Additionally, it decouples the multi-subject learning task into a two-stage training, propelling the deep model and its plugin network to learn inter-subject commonality knowledge and various cognition patterns, respectively. Wills Aligner enables us to overcome anatomical differences and to efficiently leverage a single model for multi-subject brain representation learning. We meticulously evaluate the performance of our approach across coarse-grained and fine-grained visual decoding tasks. The experimental results demonstrate that our Wills Aligner achieves state-of-the-art performance.