The invention relates to the technical field of anti-tumor treatment drugs, in particular to application of beta-glucan combined with an anti-tumor drug in anti-tumor treatment. Beta-glucan is beta-glucan polysaccharide derived from yeast and comprises beta-1,3 / 1,6 glucan, and structurally, a yeast beta-glucan main chain is formed by connecting glucose monomers through beta-(1, 3) bonds, and a side chain is connected to the main chain by glucose through a beta-(1, 6) glycosidic bond; and beta-glucan and an antibody or a small molecule drug are applied in a combined mode, the anti-tumor effectis achieved by improving the tumor immune microenvironment, beta-glucan can promote natural immune effector cells to kill complement-conditioned tumor cells through a complement CR3 dependence mechanism, and multiple animal tumor models show that compared with any monotherapy, the situation that the beta-glucan and a complement activator or an anti-tumor antibody are combined for treatment can remarkably delay the tumor growth, and the total lifetime can be prolonged.