In　recent　years,　immunotherapy　has　emerged　as　a　novel　antitumor　strategy　in　addition　to　traditional　surgery,　radiotherapy　and　chemotherapy.　It　uniquely　focuses　on　immune　cells　and　immunomodulators　in　the　tumor　microenvironment　and　helps　eliminate　tumors　at　the　root　by　rebuilding　the　immune　system.　Despite　remarkable　breakthroughs,　cancer　immunotherapy　still　faces　many　challenges:　lack　of　predictable　and　prognostic　biomarkers,　adverse　side　effects,　acquired　treatment　resistance,　high　costs,　etc.　Therefore,　more　efficacious　and　efficient,　safer　and　cheaper　antitumor　immunomodulatory　drugs　have　become　an　urgent　requirement.　For　decades,　plant-derived　natural　products　obtained　from　land　and　sea　have　provided　the　most　important　source　for　the　development　of　antitumor　drugs.　Currently,　more　attention　is　being　paid　to　the　discovery　of　potential　cancer　immunotherapy　modulators　from　plant-derived　natural　products,　such　as　polysaccharides,　phenols,　terpenoids,　quinones　and　alkaloids.　Some　of　these　agents　have　outstanding　advantages　of　multitargeting　and　low　side　effects　and　low　cost　compared　to　conventional　immunotherapeutic　agents.　We　intend　to　summarize　the　progress　of　comprehensive　research　on　these　plant-derived　natural　products　and　their　derivatives　and　discuss　their　possible　mechanisms　in　regulating　the　immune　system　and　their　efficacy　as　monotherapies　or　in　combination　with　regular　chemotherapeutic　agents.