Through a large number of experimental evaluations，oily agent，extremepressure agent，antirust agent，pH value stabilizer and defoaming agent were selected，and a environmental synthetic cutting fluid of heavy load machining was developed by rationally mixing these additives.The lubrication performance of the developed synthetic cutting fluid was tested by Four-ball test method and tapping torque method，and the antirust property of cast iron was tested by IP287 cast iron antirust test method.The results show that the developed synthetic cutting fluid has excellent lubricity，extreme-pressure，rust resistance，good cooling and cleaning property，and biological stability.Its indicators are up to the same level of imported similar products.The results of practical application show that it can meet the requirements of heavy load cutting machining of different materials instead of emulsion，micro-emulsion and oil based cutting fluid.