The invention provides a method for inducing DC-CIK by utilizing muramyl dipeptide, that is to say, the muramyl dipeptide is added into a CIK or DC-CIK culture solution to induce proliferation and differentiation of CIK or DC-CIK cells, so as to improve the tumor-killing activity of the CIK or DC-CIK cells. The method comprises the following steps: peripheral blood collection, tumor antigen acquisition, mononuclear cell separation, mononuclear cell collection, mononuclear cell washing, MDP-DC-CIK cell induction, and culture. MDP-DC-CIK cells introduced and cultured by the method are detected by a flow cytometry, the ratio of CD3+CD56+ non-MHC restricted NKT cells is found to be up to 80% or more; and at the same time, the activity of tumor killer cells is much higher than that of DC-CIK cells by conventional induction culture, and a laboratory test result of the tumor-killing percentage reaches 99% or more.