A synthetic cutting fluid was prepared and the synergistic effect between organic molybdenum and organoboron extreme pressure agents and triethanolamine borate antirust agent was studied.The tribological properties of synthetic cutting fluid were studied with fourball friction and wear tester;the antirust performance was studied through the sheet rust test and laminated rust test with grey cast iron;the surface morphology of the specimen was observed with a laser confocal microscope,and the surface roughness of the specimen was measured to investigate the influence of extreme pressure agent on the surface quality of the specimen.The results show that two kinds of extreme pressure agents have a synergistic effect,which can increase the extreme pressure lubricating factor(The ratio of the maximum nonseizure load to the friction coefficient) of synthetic cutting fluid,and improve the surface quality of the specimen.The synergistic effect between organoboron extreme pressure agent and triethanolamine borate antirust agent can enhance the antirust effect of the cutting fluid.When adding compound extreme pressure agents and antirust agent in the synthetic cutting fluid,both the extreme pressure performance and the antirust performance are increased compared with a single additive of cutting fluid,indicatingthe compound extreme pressure agents have a synergistic effect with antirust agent.