MixFormer is an end-to-end vision transformer architecture designed for visual object tracking in computer vision. Unlike traditional tracking frameworks that separate feature extraction and target-search relation modeling into distinct multi-stage processes, MixFormer unifies these operations using iterative mixed attention modules. These modules simultaneously perform self-attention within individual image regions and cross-attention between target templates and the search area, enabling the model to extract target-specific features while facilitating continuous information exchange across frames. Constructed by stacking these mixed attention layers with patch embeddings and a localization head, the architecture simplifies the tracking pipeline and efficiently supports dynamic template updates to accurately track moving objects in video sequences.