In recent years, deep learning technology has made remarkable progress in many computer vision tasks. More and more researchers have tried to apply it to medical image processing, such as the segmentation of an atomical structures in high-throughput medical images (CT, MRI), which can improve the efficiency of image reading for doctors. Deep learning models for training medical image processing need a large amount of labeled data, and the data from a separate medical institution can not meet this requirement. Moreover, due to the difference in medical equipment and acquisition protocols, the data from different medical institutions are largely heterogeneous. This results in the difficulty in obtaining reliable results on the data of a certain medical institution with the model trained by data from other medical institutions. In addition, the distribution of different medical data in patients’ disease stages is uneven, thereby reducing the reliability of the model. Technologies including domain adaptation and multi-site learning emerge to reduce the impact of data heterogeneity and improve the generalization ability of the model. As a research hotspot in transfer learning, domain adaptation is intended to transfer knowledge learned from the source domain to data of the unlabeled target domain. Multi-site learning and federated learning with non-independent and identically distributed data aim to improve the robustness of the model by learning a common representation on multiple datasets. This study investigates, analyzes, and summarizes domain adaptation, multi-site learning, and federated learning with non-independent and identically distributed datasets in recent years, providing references for related research.