HighlightsSystematic summary of ligand engineering in Sn-based perovskite solar cells at the molecular level (oxidation-suppression), crystal structural level (bulk-defect passivation and crystal orientation optimization), and film level (film stability).The classification and composition of ligand engineering in the review are the same as the actual preparation process, which will help researchers to understand the role of ligands in combination with the actual experiment process.Description of ligands focuses on the function of each functional group; the relevant conclusion can be universal.