The invention relates to a Y2Ti2O7/stainless steel function gradient composite material and a preparation method thereof. The preparation method includes the steps that according to the volume percent, a plurality of parts of gradient layer mixed powder materials with Y2Ti2O7 and stainless steel mixed at different percentages are prepared; pure Y2Ti2O7 powder, the multiple parts of the gradient layer mixed powder materials and pure stainless steel powder are sequentially and evenly laid in a mold according to the gradient; and then the materials in the mold are subjected to vacuum hot-pressing sintering, so that the function gradient composite material is obtained. The function gradient composite material prepared through the method solves the problem that the two phases of Y2Ti2O7 ceramic and stainless steel are not matched due to the coefficient of thermal expansion, and effectively combines the heat resistance of the Y2Ti2O7 ceramic with the good mechanical property of the stainless steel.