Abstract: The present invention provides an application of nano copper in a cutting fluid. The nano copper is self-dispersible nano copper with an organic long-carbon chain, wherein the surface of copper metal is coated with a long carbon chain organic matter, and the long chain organic matter is dialkyl dithiophosphoric acid (HDDP) and a derivative thereof. In the present invention, the nano copper substitutes functional additives which comprises one or more of a preservative, an anti-rust agent, a sterilizing agent, a compression-resisting agent and a lubricant to solve the technical problems of the existing fluid in the prior art being unable to simultaneously have efficient anti-corrosion, anti-rust, compression-resistant, lubricating and sterilizing properties as well as the variety, the relatively high amount, the high cost and the limited selection of added additives.