The invention discloses a preparation method of an ultra-fine grain high-dense high-copper-content Cu-W alloy and belongs to the field of metal and alloy materials of the metal. Firstly, Cu powder andW powder are weighed and mixed according to the proportion, then put in a ball milling tank to be subjected to ball milling and cooled to the indoor temperature after being subjected to ball milling,so that Cu-W mixed powder is obtained; a graphite die is filled with the Cu-W mixed powder; then, the graphite die is placed in a plasma activated sintering furnace to be subjected to vacuum pressuresintering, and a sintered Cu-W alloy is obtained; and the sintered Cu-W alloy is put in a heating furnace and heated to the temperature between 955 DEG C and 985 DEG C under the protection of high-purity hydrogen gas, the temperature is kept for 5 min to 10 min, the sintered Cu-W alloy is taken out and quickly placed in a liquid nitrogen environment, the pressure between 600 MPa and 800 MPa is applied, and the temperature and the pressure are kept for 2 h. The grain of the finished product Cu-W alloy prepared through the above method is as fine as 10 nm, and the density is high. The preparedultra-fine grain high-dense high-copper-content Cu-W alloy has wide application prospects in the fields of electronics, the war industry, aerospace and the like.