Transmembrane　proteins　(TMEMs)　are　integrated　membrane　proteins　that　span　the　entire　lipid　bilayer　and　are　permanently　anchored　to　it.　TMEMs　participate　in　various　cellular　processes.　Some　TMEMs　usually　exist　and　perform　their　physiological　functions　as　dimers　rather　than　monomers.　TMEM　dimerization　is　associated　with　various　physiological　functions,　such　as　the　regulation　of　enzyme　activity,　signal　transduction,　and　cancer　immunotherapy.　In　this　review,　we　focus　on　the　dimerization　of　transmembrane　proteins　in　cancer　immunotherapy.　This　review　is　divided　into　three　parts.　First,　the　structures　and　functions　of　several　TMEMs　related　to　tumor　immunity　are　introduced.　Second,　the　characteristics　and　functions　of　several　typical　TMEM　dimerization　processes　are　analyzed.　Finally,　the　application　of　the　regulation　of　TMEM　dimerization　in　cancer　immunotherapy　is　introduced.