Abstract: To improve chip removal performance during drilling of titanium alloy deep hole annular trepanning. TC4 titanium alloy bar was selected as the research object, and the optimization of cutting fluid parameters for deep hole annular trepanning drilling was carried out based on box-behnken design (BBD) response surface methodology combined with simulation tests. The three parameters of input condition are cutting fluid density, cutting fluid viscosity and cutting fluid flow rate, and the optimization objectives are chipbreaker pressure and chipbreaker turbulence kinetic energy of the first cutter tooth, so as to establish a regression model between the influencing factors and the response values. Explore the law of influence of the three parameters on the response values. The experimental results show that the interaction of cutting fluid viscosity and flow rate has the greatest influence on the two response values. The optimal parameters of cutting fluid are density 1 100 kg/m³, viscosity 0.002 kg/(m·s), flow rate 180 L/min. Physical test validation shows that the optimized cutting fluid can obviously improve the chip morphology, which is conducive to improving the chip removal performance.