The invention relates to a method for in-vitro inducing amplification of type-I NKT (natural killer T) cells. With a mode of 'specificity stimulant + staged cytokine', the method includes two culture phases. The first culture phase focuses on specific amplification of the number of the type-I NKT cells, wherein the specificity stimulant alpha-GalCer is used for preferential amplification of the type-I NKT cells, CD1d expression cells supported with alpha-GalCer stimulate the type-I NKT cells to amplify continuously, and the cytokines IL-2 and IL-7 are added to assist the type-I NKT cells in growing; in the second culture phase, amplification of the number of the type-I NKT cells and guide function directional differentiation are conducted, the CD1d expression cells incubated by the alpha-GalCer continue to stimulate amplification of the type-I NKT cells, the cytokines IL-2, IL-7 and IL-15 are added simultaneously to assist the type-I NKT cells in amplification and guide differentiation, and in a culture system 1-2 days before culture is finished, the cytokines IL-12 are added to guide further directional differentiation of the type-I NKT cells, so that killing activity is enhanced. The method for in-vitro inducing amplification of the type-I NKT cells is simple to operate, capable of enhancing killing activity of amplification products while achieving in-vitro mass amplification of the type-I NKT cells and suitable for scale production.