Micro-groove heat pipe is a good choice for heat dissipation of large CNC lathes. Its thermal conductivity is limited by a variety of heat transfer limits, which mainly depend on the geometrical parameters, the status of working fluid, the structure of the wick and the working temperature. Through mathematical modeling the optimized geometric parameters are chosen as 9.38 mm inner hole diameter and 55 grooves with 0.32 mm top side width, 0.31 mm groove depth, 0.31458 mm bottom width. Analysis of gas-liquid two-phase flow is taken to find out that the best filling rate is 22.62% for the working fluid. An orthogonal experiment is also carried out to get the suitable length, working temperature and inclination angle for the micro-groove heat pipe. From the experimental results, the heating temperature is found to have the largest impact on the heat transfer rate, followed by the heat pipe length, and the inclination angle has the least impact. Moreover, 50°C bath temperature, 160 mm heat pipe length and 90° inclination angle are the most suitable environmental parameters for the flat micro-groove heat pipe under the experimental circumstance. © 2023, Politechnica University of Bucharest. All rights reserved.