The invention provides a Cu2-xS thermoelectric material preparation method. The method includes the steps of preparing CuS powder through a co-precipitation method, heating the CuS powder in an inert atmosphere to be decompose into Cu2-xS and S, repeatedly washing solid powder obtained after heating with an organic solvent (CCl4 or CS2) and absolute ethyl alcohol to remove S, subjecting the solid powder removed with S to vacuum drying to obtain Cu2-xS powder, and making the Cu2-xS powder into a Cu2-xS thermoelectric material in block through pressure sintering. According to the Cu2-xS thermoelectric material preparation method, the Cu soluble salt of low cost and sulfur ion soluble salt are used as raw materials for producing CuS powder and the CuS powder is decomposed in high-temperature inert gas, washed and sintered to obtain the Cu2-xS thermoelectric material without devices such as, a glove box and a quartz sealed tube. Compared with existing preparation methods, the Cu2-xS thermoelectric material preparation method has the advantages of being low in production cost, low in equipment requirement, easy to operate, high in safety, capable of achieving batch production easily and the like. Meanwhile, the prepared Cu2-xS thermoelectric material is high in conductivity and good in performance.