The invention discloses a papillary thyroid carcinoma lymph node metastasis prediction method based on Transform-MIL. The method comprises the following steps: S1, extracting the characteristics of patch in WSI by using a lightweight ViT network; s2, selecting a key path by adopting a clustering-based strategy; s3, constructing a Transform-MIL model, learning relationships among instances from multiple aspects through a multi-head self-attention mechanism, and embedding instance-level features into packet representation; s4, combining a thyroid papillary set and a lymph node metastasis data set, and helping a Transform-MIL model to learn and predict lymph node metastasis through mutual knowledge distillation; according to the method, the Transform-MIL model is constructed, the instance-level features are better embedded into the packet representation, the morphological similarity between the tumor cells and the lymph node metastasis cells is fully utilized, and the knowledge of the relationship between the two data sets is transmitted by taking the attention map as a medium, so that the prediction accuracy of the lymph node metastasis histopathology image is improved.