This study focuses on the optimization of the machining assisted by cryogenic cooling. The main objective is to analyze the effect of the pressure and the flow of liquid nitrogen on tool life when machining titanium alloy Ti-6Al-4V using the cryogenic assisted machining. A nozzle holder has been specially developed for this study to ensure positioning and the replacement of calibrated nozzles of different diameters. Several nozzle diameters have been therefore used in order to vary the pressure and the flow according to tests to be conducted. The flow rate has been varied between 1.2 l/min and 3.4 l/min for two pressure ranges 8-10 bar and 4-5 bar respectively.The machining tests have allowed to highlight the effect of the pressure and flow rate of liquid nitrogen jet on the tool life. Indeed, the results showed that increasing the flow rate increases the tool life. In addition, the increase in pressureslowed down the evolution of the wear and further improves the tool life.Indeed, in all tested cases, the cryogenic assistance improves the tool life but the best results have been obtained for the highest pressure and flow rate. Moreover, surface integrity has been greatly improved